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33 hoursall: prealloc slice with possible minimum capabilitiesShulhan
2025-10-17all: remove unnecessary loop variable copies in testsTobias Klauser
Copying the loop variable is no longer necessary since Go 1.22. Change-Id: Iebb21dac44a20ec200567f1d786f105a4ee4999d Reviewed-on: https://go-review.googlesource.com/c/go/+/711640 Reviewed-by: Florian Lehner <lehner.florian86@gmail.com> Auto-Submit: Damien Neil <dneil@google.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> Reviewed-by: Damien Neil <dneil@google.com> Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2025-04-11all: use built-in min, max functionsMarcel Meyer
Change-Id: Ie76ebb556d635068342747f3f91dd7dc423df531 GitHub-Last-Rev: aea61fb3a054e6bd24f4684f90fb353d5682cd0b GitHub-Pull-Request: golang/go#73340 Reviewed-on: https://go-review.googlesource.com/c/go/+/664677 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Auto-Submit: Keith Randall <khr@golang.org> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> Reviewed-by: Keith Randall <khr@golang.org> Reviewed-by: Keith Randall <khr@google.com>
2024-10-21runtime,time: use atomic.Int32 for isSendingMichael Anthony Knyszek
This change switches isSending to be an atomic.Int32 instead of an atomic.Uint8. The Int32 version is managed as a counter, which is something that we couldn't do with Uint8 without adding a new intrinsic which may not be available on all architectures. That is, instead of only being able to support 8 concurrent timer firings on the same timer because we only have 8 independent bits to set for each concurrent timer firing, we can now have 2^31-1 concurrent timer firings before running into any issues. Like the fact that each bit-set was matched with a clear, here we match increments with decrements to indicate that we're in the "sending on a channel" critical section in the timer code, so we can report the correct result back on Stop or Reset. We choose an Int32 instead of a Uint32 because it's easier to check for obviously bad values (negative values are always bad) and 2^31-1 concurrent timer firings should be enough for anyone. Previously, we avoided anything bigger than a Uint8 because we could pack it into some padding in the runtime.timer struct. But it turns out that the type that actually matters, runtime.timeTimer, is exactly 96 bytes in size. This means its in the next size class up in the 112 byte size class because of an allocation header. We thus have some free space to work with. This change increases the size of this struct from 96 bytes to 104 bytes. (I'm not sure if runtime.timer is often allocated directly, but if it is, we get lucky in the same way too. It's exactly 80 bytes in size, which means its in the 96-byte size class, leaving us with some space to work with.) Fixes #69969. Related to #69880 and #69312. Change-Id: I9fd59cb6a69365c62971d1f225490a65c58f3e77 Cq-Include-Trybots: luci.golang.try:gotip-linux-amd64-longtest Reviewed-on: https://go-review.googlesource.com/c/go/+/621616 Reviewed-by: Ian Lance Taylor <iant@google.com> Auto-Submit: Michael Knyszek <mknyszek@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2024-10-14runtime: don't frob isSending for tickersIan Lance Taylor
The Ticker Stop and Reset methods don't report a value, so we don't need to track whether they are interrupting a send. This includes a test that used to fail about 2% of the time on my laptop when run under x/tools/cmd/stress. Change-Id: Ic6d14b344594149dd3c24b37bbe4e42e83f9a9ad Reviewed-on: https://go-review.googlesource.com/c/go/+/620136 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Ian Lance Taylor <iant@google.com> Auto-Submit: Michael Knyszek <mknyszek@google.com> Auto-Submit: Ian Lance Taylor <iant@google.com> Reviewed-by: Michael Knyszek <mknyszek@google.com>
2024-09-26runtime: if stop/reset races with running timer, return correct resultIan Lance Taylor
The timer code is careful to ensure that if stop/reset is called while a timer is being run, we cancel the run. However, the code failed to ensure that in that case stop/reset returned true, meaning that the timer had been stopped. In the racing case stop/reset could see that t.when had been set to zero, and return false, even though the timer had not and never would fire. Fix this by tracking whether a timer run is in progress, and using that to reliably detect that the run was cancelled, meaning that stop/reset should return true. Fixes #69312 Change-Id: I78e870063eb96650638f12c056e32c931417c84a Reviewed-on: https://go-review.googlesource.com/c/go/+/611496 Reviewed-by: David Chase <drchase@google.com> Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com> Reviewed-by: Michael Knyszek <mknyszek@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Auto-Submit: Ian Lance Taylor <iant@golang.org>
2024-03-22runtime: add fast path for (*timers).adjustIan Lance Taylor
Affected benchmark results, including new benchmark (some of these may just be noise, of course): AdjustTimers10000-12 797.7µ ± 2% 709.6µ ± 2% -11.04% (p=0.000 n=10) TickerResetNaive-12 62.69n ± 1% 63.56n ± 1% +1.40% (p=0.018 n=10) NowUnixMicro-12 29.95n ± 1% 30.25n ± 4% +1.00% (p=0.024 n=10) ParseDuration-12 81.88n ± 0% 81.45n ± 0% -0.51% (p=0.006 n=10) UnmarshalText-12 186.9n ± 1% 185.2n ± 1% -0.88% (p=0.006 n=10) geomean 151.8n 151.2n -0.40% Change-Id: I3ef8356249c5d703b314498e34ee8095093671c8 Reviewed-on: https://go-review.googlesource.com/c/go/+/573455 Reviewed-by: Austin Clements <austin@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Auto-Submit: Ian Lance Taylor <iant@google.com> Reviewed-by: Ian Lance Taylor <iant@google.com> Commit-Queue: Ian Lance Taylor <iant@google.com>
2024-03-14time: replace time.Now().Sub call with time.Since in testguoguangwu
Change-Id: I56ca2d11637d60c6b0656fdc1d900a2384aba141 GitHub-Last-Rev: 686e02db77797fd81aafcde8ae40c85cee8dd817 GitHub-Pull-Request: golang/go#66264 Reviewed-on: https://go-review.googlesource.com/c/go/+/570916 Reviewed-by: qiulaidongfeng <2645477756@qq.com> Auto-Submit: Ian Lance Taylor <iant@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com> Reviewed-by: Ian Lance Taylor <iant@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2024-03-14runtime: fix lost sleep causing TestZeroTimer flakesRuss Cox
Classic operating system kernel mistake: if you start using per-CPU data without disabling interrupts on the CPU, and then an interrupt reschedules the process onto a different CPU, now you're using the wrong CPU's per-CPU data. The same thing happens in Go if you use per-M or per-P data structures while not holding a lock nor using acquirem. In the original timer.modify before CL 564977, I had been very careful about this during the "unlock t; lock ts" dance, only calling releasem after ts was locked. That made sure we used the right ts. The refactoring of that code into its own helper function in CL 564977 missed that nuance. The code ts := &getg().m.p.p.ptr().timers ts.lock() was now executing without holding any locks nor acquirem. If the goroutine changed its M or P between deciding which ts to use and actually locking that ts, the code would proceed to add the timer t to some other P's timers. If the P was idle by then, the scheduler could have already checked it for timers and not notice the newly added timer when deciding when the next timer should trigger. The solution is to do what the old code correctly did, namely acquirem before deciding which ts to use, rather than assume getg().m.p won't change before ts.lock can complete. This CL does that. Before CL 564977, stress ./time.test -test.run='ZeroTimer/impl=(func|cache)' -test.timeout=3m -test.count=20 ran without failure for over an hour on my laptop. Starting in CL 564977, it consistently failed within a few minutes. After this CL, it now runs without failure for over an hour again. Fixes #66006. Change-Id: Ib9e7ccaa0f22a326ce3fdef2b9a92f7f0bdafcbf Reviewed-on: https://go-review.googlesource.com/c/go/+/571196 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Auto-Submit: Russ Cox <rsc@golang.org> Reviewed-by: Ian Lance Taylor <iant@google.com>
2024-03-13time: garbage collect unstopped Tickers and TimersRuss Cox
From the beginning of Go, the time package has had a gotcha: if you use a select on <-time.After(1*time.Minute), even if the select finishes immediately because some other case is ready, the underlying timer from time.After keeps running until the minute is over. This pins the timer in the timer heap, which keeps it from being garbage collected and in extreme cases also slows down timer operations. The lack of garbage collection is the more important problem. The docs for After warn against this scenario and suggest using NewTimer with a call to Stop after the select instead, purely to work around this garbage collection problem. Oddly, the docs for NewTimer and NewTicker do not mention this problem, but they have the same issue: they cannot be collected until either they are Stopped or, in the case of Timer, the timer expires. (Tickers repeat, so they never expire.) People have built up a shared knowledge that timers and tickers need to defer t.Stop even though the docs do not mention this (it is somewhat implied by the After docs). This CL fixes the garbage collection problem, so that a timer that is unreferenced can be GC'ed immediately, even if it is still running. The approach is to only insert the timer into the heap when some channel operation is blocked on it; the last channel operation to stop using the timer takes it back out of the heap. When a timer's channel is no longer referenced, there are no channel operations blocked on it, so it's not in the heap, so it can be GC'ed immediately. This CL adds an undocumented GODEBUG asynctimerchan=1 that will disable the change. The documentation happens in the CL 568341. Fixes #8898. Fixes #61542. Change-Id: Ieb303b6de1fb3527d3256135151a9e983f3c27e6 Reviewed-on: https://go-review.googlesource.com/c/go/+/512355 Reviewed-by: Austin Clements <austin@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Auto-Submit: Russ Cox <rsc@golang.org>
2024-03-13time: clean up benchmarksRuss Cox
Comparing BenchmarkStop against very old commits like CL 13094043, I was very confused about how timers had gotten almost 10X slower since 2013. It turns out that CL 68060043 introduced a factor of 1000 in the benchmark cost, by counting batches of 1000 as 1 op instead of 1000 ops, and timers have actually gotten dramatically faster since 2013, with the addition of per-P timer heaps and other optimizations. This CL rewrites the benchmarks to use testing.PB directly, so that the factor of 1000 disappears, and "/op" really means "/op". In the few tests that need to run in batches for one reason or another, add "1000" to the name to make clear that batches are being run. Change-Id: I27ed74d1e420934982e4205aad4f218cdfc42509 Reviewed-on: https://go-review.googlesource.com/c/go/+/570495 Auto-Submit: Russ Cox <rsc@golang.org> Reviewed-by: Ian Lance Taylor <iant@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2024-03-11time: fix typo in BenchmarkResetqiulaidongfeng
Change-Id: I1dbd1c5aa26f458cdac7a3f0ca974254a069311f GitHub-Last-Rev: da481ba7a9082a5fae5cc7c72821167d9879f54f GitHub-Pull-Request: golang/go#66219 Reviewed-on: https://go-review.googlesource.com/c/go/+/569897 Reviewed-by: Ian Lance Taylor <iant@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Auto-Submit: Ian Lance Taylor <iant@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com>
2024-03-08time: make sure tests avoid the special-case channel codeRuss Cox
Many of the tests in package time are about proper manipulation of the timer heap. But now NewTimer bypasses the timer heap except when something is blocked on the associated channel. Make the tests test the heap again by using AfterFunc instead of NewTimer. In particular, adds a non-chan version of TestZeroTimer, which was flaky-broken and then fixed by CLs in the cleanup stack. This new tests makes sure we notice if it breaks again. Fixes #66006. Change-Id: Ib59fc1b8b85ef5a21e72fe418c627c9b8b8a083a Reviewed-on: https://go-review.googlesource.com/c/go/+/568255 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Ian Lance Taylor <iant@google.com> Auto-Submit: Russ Cox <rsc@golang.org> Reviewed-by: Austin Clements <austin@google.com>
2024-02-27runtime: disable use of runnext on wasmMichael Pratt
When readying a goroutine, the scheduler typically places the readied goroutine in pp.runnext, which will typically be the next goroutine to run in the schedule. In order to prevent a set of ping-pong goroutines from simply switching back and forth via runnext and starving the rest of the run queue, a goroutine scheduled via runnext shares a time slice (pp.schedtick) with the previous goroutine. sysmon detects "long-running goroutines", which really means Ps using the same pp.schedtick for too long, and preempts them to allow the rest of the run queue to run. Thus this avoids starvation via runnext. However, wasm has no threads, and thus no sysmon. Without sysmon to preempt, the possibility for starvation returns. Avoid this by disabling runnext entirely on wasm. This means that readied goroutines always go on the end of the run queue and thus cannot starve via runnext. Note that this CL doesn't do anything about single long-running goroutines. Without sysmon to preempt them, a single goroutine that fails to yield will starve the run queue indefinitely. For #65178. Change-Id: I10859d088776125a2af8c9cd862b6e071da628b5 Cq-Include-Trybots: luci.golang.try:gotip-js-wasm,gotip-wasip1-wasm_wasmtime,gotip-wasip1-wasm_wazero Reviewed-on: https://go-review.googlesource.com/c/go/+/559798 Auto-Submit: Bryan Mills <bcmills@google.com> Reviewed-by: Michael Pratt <mpratt@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2024-02-19runtime: use a high res timer to signal io completion ports on windowsqmuntal
GetQueuedCompletionStatusEx has a ~16ms timeout resolution. Use a WaitCompletionPacket associated with the I/O Completion Port (IOCP) and a high resolution timer so the IOCP is signaled on timer expiry, therefore improving the GetQueuedCompletionStatusEx timeout resolution. BenchmarkSleep from the time package shows an important improvement: goos: windows goarch: amd64 pkg: time cpu: Intel(R) Core(TM) i7-10850H CPU @ 2.70GHz │ old.txt │ new.txt │ │ sec/op │ sec/op vs base │ Sleep-12 1258.5µ ± 5% 250.7µ ± 1% -80.08% (p=0.000 n=20) Fixes #44343. Change-Id: I79fc09e34dddfc49e0e23c3d1d0603926c22a11d Reviewed-on: https://go-review.googlesource.com/c/go/+/488675 Reviewed-by: Alex Brainman <alex.brainman@gmail.com> Run-TryBot: Quim Muntal <quimmuntal@gmail.com> TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Bryan Mills <bcmills@google.com> Reviewed-by: Michael Knyszek <mknyszek@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2024-01-30Revert "runtime: disable use of runnext on wasm"Michael Pratt
This reverts CL 557437. Reason for revert: Appears to have broken wasip1 builders. For #65178. Change-Id: I59c1a310eb56589c768536fe444c1efaf862f8b0 Reviewed-on: https://go-review.googlesource.com/c/go/+/559237 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Auto-Submit: Michael Pratt <mpratt@google.com> Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
2024-01-29runtime: disable use of runnext on wasmMichael Pratt
When readying a goroutine, the scheduler typically places the readied goroutine in pp.runnext, which will typically be the next goroutine to run in the schedule. In order to prevent a set of ping-pong goroutines from simply switching back and forth via runnext and starving the rest of the run queue, a goroutine scheduled via runnext shares a time slice (pp.schedtick) with the previous goroutine. sysmon detects "long-running goroutines", which really means Ps using the same pp.schedtick for too long, and preempts them to allow the rest of the run queue to run. Thus this avoids starvation via runnext. However, wasm has no threads, and thus no sysmon. Without sysmon to preempt, the possibility for starvation returns. Avoid this by disabling runnext entirely on wasm. This means that readied goroutines always go on the end of the run queue and thus cannot starve via runnext. Note that this CL doesn't do anything about single long-running goroutines. Without sysmon to preempt them, a single goroutine that fails to yield will starve the run queue indefinitely. For #65178. Cq-Include-Trybots: luci.golang.try:gotip-js-wasm,gotip-wasip1-wasm_wasmtime,gotip-wasip1-wasm_wazero Change-Id: I7dffe1e72c6586474186b72f8068cff77b661eae Reviewed-on: https://go-review.googlesource.com/c/go/+/557437 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Mauri de Souza Meneguzzo <mauri870@gmail.com> Reviewed-by: Michael Knyszek <mknyszek@google.com> Reviewed-by: Bryan Mills <bcmills@google.com>
2024-01-22time: add a regression test for time.AfterFunc goroutine starvationBryan C. Mills
The test is skipped on wasm platforms for now, because it successfully detects a starvation bug on those platforms. For #65178. Change-Id: I05d28f1c7be99fcab67ec4dfaa38f412e11fd3cb Reviewed-on: https://go-review.googlesource.com/c/go/+/557038 Auto-Submit: Bryan Mills <bcmills@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Damien Neil <dneil@google.com>
2023-07-11time: increase arbitrary upper bound in TestReset to 10sBryan C. Mills
The previous upper bound was around 0.375 s, which is empirically too short on a slow, heavily-loaded builder. Since the test doesn't seem to depend on the actual duration in any meaningful way, let's make it several orders of magnitude larger. Fixes #61266. Change-Id: I6dde5e174966ee385db67e3cb87334f463c7e597 Reviewed-on: https://go-review.googlesource.com/c/go/+/508695 TryBot-Result: Gopher Robot <gobot@golang.org> Run-TryBot: Bryan Mills <bcmills@google.com> Reviewed-by: Ian Lance Taylor <iant@google.com>
2022-09-05runtime: convert local var stop at TestAfterStress to atomic typecuiweixie
For #53821 Change-Id: I7e86dac34691f7752f68879ff379061f3435cd45 Reviewed-on: https://go-review.googlesource.com/c/go/+/427139 Reviewed-by: Michael Knyszek <mknyszek@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Run-TryBot: xie cui <523516579@qq.com> Reviewed-by: Heschi Kreinick <heschi@google.com>
2022-01-06time: skip TestTimerModifiedEarlier on plan9/armBryan C. Mills
This test is observed to be flaky on the plan9-arm builder. Skip it on that platform until it can be diagnosed and fixed. For #50470 Change-Id: If626af426d856c377e00ac5baaca52899456556e Reviewed-on: https://go-review.googlesource.com/c/go/+/375934 Trust: Bryan Mills <bcmills@google.com> Run-TryBot: Bryan Mills <bcmills@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2021-09-15runtime: in adjustTimers back up as far as necessaryIan Lance Taylor
When the adjustTimers function removed a timer it assumed it was sufficient to continue the heap traversal at that position. However, in some cases a timer will be moved to an earlier position in the heap. If that timer is timerModifiedEarlier, that can leave timerModifiedEarliest not correctly representing the earlier such timer. Fix the problem by restarting the heap traversal at the earliest changed position. Fixes #47762 Change-Id: I152bbe62793ee40a680baf49967bcb89b1f94764 Reviewed-on: https://go-review.googlesource.com/c/go/+/343882 Trust: Ian Lance Taylor <iant@golang.org> Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Michael Knyszek <mknyszek@google.com>
2021-07-22runtime: don't clear timerModifiedEarliest if adjustTimers is 0Ian Lance Taylor
This avoids a race when a new timerModifiedEarlier timer is created by a different goroutine. Fixes #47329 Change-Id: I6f6c87b4a9b5491b201c725c10bc98e23e0ed9d1 Reviewed-on: https://go-review.googlesource.com/c/go/+/336432 Trust: Ian Lance Taylor <iant@golang.org> Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Michael Knyszek <mknyszek@google.com>
2021-03-10runtime, time: disable preemption in addtimerMichael Pratt
The timerpMask optimization updates a mask of Ps (potentially) containing timers in pidleget / pidleput. For correctness, it depends on the assumption that new timers can only be added to a P's own heap. addtimer violates this assumption if it is preempted after computing pp. That G may then run on a different P, but adding a timer to the original P's heap. Avoid this by disabling preemption while pp is in use. Other uses of doaddtimer should be OK: * moveTimers: always moves to the current P's heap * modtimer, cleantimers, addAdjustedTimers, runtimer: does not add net new timers to the heap while locked Fixes #44868 Change-Id: I4a5d080865e854931d0a3a09a51ca36879101d72 Reviewed-on: https://go-review.googlesource.com/c/go/+/300610 Trust: Michael Pratt <mpratt@google.com> Run-TryBot: Michael Pratt <mpratt@google.com> Reviewed-by: Michael Knyszek <mknyszek@google.com> Reviewed-by: Ian Lance Taylor <iant@golang.org> TryBot-Result: Go Bot <gobot@golang.org>
2020-12-03runtime, time: strictly enforce when, period constraintsMichael Pratt
timer.when must always be positive. addtimer and modtimer already check that it is non-negative; we expand it to include zero. Also upgrade from pinning bad values to throwing, as these values shouldn't be possible to pass (except as below). timeSleep may overflow timer.nextwhen. This would previously have been pinned by resetForSleep, now we fix it manually. runOneTimer may overflow timer.when when adding timer.period. Detect this and pin to maxWhen. addtimer is now too strict to allow TestOverflowRuntimeTimer to test an overflowed timer. Such a timer should not be possible; to help guard against accidental inclusion siftup / siftdown will check timers as it goes. This has been replaced with tests for period and sleep overflows. Change-Id: I17f9739e27ebcb20d87945c635050316fb8e9226 Reviewed-on: https://go-review.googlesource.com/c/go/+/274853 Trust: Michael Pratt <mpratt@google.com> Reviewed-by: Michael Knyszek <mknyszek@google.com> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2020-10-27runtime: reduce timer latencyChris Hines
Change the scheduler to treat expired timers with the same approach it uses to steal runnable G's. Previously the scheduler ignored timers on P's not marked for preemption. That had the downside that any G's waiting on those expired timers starved until the G running on their P completed or was preempted. That could take as long as 20ms if sysmon was in a 10ms wake up cycle. In addition, a spinning P that ignored an expired timer and found no other work would stop despite there being available work, missing the opportunity for greater parallelism. With this change the scheduler no longer ignores timers on non-preemptable P's or relies on sysmon as a backstop to start threads when timers expire. Instead it wakes an idle P, if needed, when creating a new timer because it cannot predict if the current P will have a scheduling opportunity before the new timer expires. The P it wakes will determine how long to sleep and block on the netpoller for the required time, potentially stealing the new timer when it wakes. This change also eliminates a race between a spinning P transitioning to idle concurrently with timer creation using the same pattern used for submission of new goroutines in the same window. Benchmark analysis: CL 232199, which was included in Go 1.15 improved timer latency over Go 1.14 by allowing P's to steal timers from P's not marked for preemption. The benchmarks added in this CL measure that improvement in the ParallelTimerLatency benchmark seen below. However, Go 1.15 still relies on sysmon to notice expired timers in some situations and sysmon can sleep for up to 10ms before waking to check timers. This CL fixes that shortcoming with modest regression on other benchmarks. name \ avg-late-ns go14.time.bench go15.time.bench fix.time.bench ParallelTimerLatency-8 17.3M ± 3% 7.9M ± 0% 0.2M ± 3% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=1-8 53.4k ±23% 50.7k ±31% 252.4k ± 9% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=2-8 204k ±14% 90k ±58% 188k ±12% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=3-8 1.17M ± 0% 0.11M ± 5% 0.11M ± 2% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=4-8 1.81M ±44% 0.10M ± 4% 0.10M ± 2% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=5-8 2.28M ±66% 0.09M ±13% 0.08M ±21% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=6-8 2.84M ±85% 0.07M ±15% 0.07M ±18% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=7-8 2.13M ±27% 0.06M ± 4% 0.06M ± 9% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=8-8 2.63M ± 6% 0.06M ±11% 0.06M ± 9% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=9-8 3.32M ±17% 0.06M ±16% 0.07M ±14% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=10-8 8.46M ±20% 4.37M ±21% 5.03M ±23% StaggeredTickerLatency/work-dur=2ms/tickers-per-P=1-8 1.02M ± 1% 0.20M ± 2% 0.20M ± 2% name \ max-late-ns go14.time.bench go15.time.bench fix.time.bench ParallelTimerLatency-8 18.3M ± 1% 8.2M ± 0% 0.5M ±12% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=1-8 141k ±19% 127k ±19% 1129k ± 3% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=2-8 2.78M ± 4% 1.23M ±15% 1.26M ± 5% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=3-8 6.05M ± 5% 0.67M ±56% 0.81M ±33% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=4-8 7.93M ±20% 0.71M ±46% 0.76M ±41% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=5-8 9.41M ±30% 0.92M ±23% 0.81M ±44% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=6-8 10.8M ±42% 0.8M ±41% 0.8M ±30% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=7-8 9.62M ±24% 0.77M ±38% 0.88M ±27% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=8-8 10.6M ±10% 0.8M ±32% 0.7M ±27% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=9-8 11.9M ±36% 0.6M ±46% 0.8M ±38% StaggeredTickerLatency/work-dur=300µs/tickers-per-P=10-8 36.8M ±21% 24.7M ±21% 27.5M ±16% StaggeredTickerLatency/work-dur=2ms/tickers-per-P=1-8 2.12M ± 2% 1.02M ±11% 1.03M ± 7% Other time benchmarks: name \ time/op go14.time.bench go15.time.bench fix.time.bench AfterFunc-8 137µs ± 4% 123µs ± 4% 131µs ± 2% After-8 212µs ± 3% 195µs ± 4% 204µs ± 7% Stop-8 165µs ± 6% 156µs ± 2% 151µs ±12% SimultaneousAfterFunc-8 260µs ± 3% 248µs ± 3% 284µs ± 2% StartStop-8 65.8µs ± 9% 64.4µs ± 7% 67.3µs ±15% Reset-8 13.6µs ± 2% 9.6µs ± 2% 9.1µs ± 4% Sleep-8 307µs ± 4% 306µs ± 3% 320µs ± 2% Ticker-8 53.0µs ± 5% 54.5µs ± 5% 57.0µs ±11% TickerReset-8 9.24µs ± 2% 9.51µs ± 3% TickerResetNaive-8 149µs ± 5% 145µs ± 5% Fixes #38860 Updates #25471 Updates #27707 Change-Id: If52680509b0f3b66dbd1d0c13fa574bd2d0bbd57 Reviewed-on: https://go-review.googlesource.com/c/go/+/232298 Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Austin Clements <austin@google.com> Trust: Ian Lance Taylor <iant@golang.org>
2020-01-03all: fix invalid invocations of Fatalf in goroutinesEmmanuel T Odeke
Found by running the go vet pass 'testinggoroutine' that I started in CL 212920. Change-Id: Ic9462fac85dbafc437fe4a323b886755a67a1efa Reviewed-on: https://go-review.googlesource.com/c/go/+/213097 Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2019-11-15time: only fail TestAfterStop if it fails five times in a rowIan Lance Taylor
The test is inherently slightly flaky, so repeat to reduce flakiness. Fixes #35537 Change-Id: Id918d48d33c7d5e19c4f24df104adc7fbf3720f2 Reviewed-on: https://go-review.googlesource.com/c/go/+/207457 Run-TryBot: Ian Lance Taylor <iant@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Reviewed-by: Bryan C. Mills <bcmills@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
2018-08-20all: update stale test skipsDaniel Martí
Issues #10043, #15405, and #22660 appear to have been fixed, and whatever tests I could run locally do succeed, so remove the skips. Issue #7237 was closed in favor of #17906, so update its skip line. Issue #7634 was closed as it had not appeared for over three years. Re-enable it for now. An issue should be open if the test starts being skipped again. Change-Id: I67daade906744ed49223291035baddaad9f56dca Reviewed-on: https://go-review.googlesource.com/121735 Run-TryBot: Daniel Martí <mvdan@mvdan.cc> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2018-04-06time: simplify comparison in testVeselkov Konstantin
Found using go-simple. Change-Id: I349e80a8c083688539bb4267564f02e3d7913da5 Reviewed-on: https://go-review.googlesource.com/105195 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-12-01Revert "go/printer: forbid empty line before first comment in block"Joe Tsai
This reverts commit 08f19bbde1b01227fdc2fa2d326e4029bb74dd96. Reason for revert: The changed transformation takes effect on a larger set of code snippets than expected. For example, this: func foo() { // Comment bar() } becomes: func foo() { // Comment bar() } This is an unintended consequence. Change-Id: Ifca88d6267dab8a8170791f7205124712bf8ace8 Reviewed-on: https://go-review.googlesource.com/81335 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Run-TryBot: Joe Tsai <joetsai@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-11-02go/printer: forbid empty line before first comment in blockJoe Tsai
To improve readability when exported fields are removed, forbid the printer from emitting an empty line before the first comment in a const, var, or type block. Also, when printing the "Has filtered or unexported fields." message, add an empty line before it to separate the message from the struct or interfact contents. Before the change: <<< type NamedArg struct { // Name is the name of the parameter placeholder. // // If empty, the ordinal position in the argument list will be // used. // // Name must omit any symbol prefix. Name string // Value is the value of the parameter. // It may be assigned the same value types as the query // arguments. Value interface{} // contains filtered or unexported fields } >>> After the change: <<< type NamedArg struct { // Name is the name of the parameter placeholder. // // If empty, the ordinal position in the argument list will be // used. // // Name must omit any symbol prefix. Name string // Value is the value of the parameter. // It may be assigned the same value types as the query // arguments. Value interface{} // contains filtered or unexported fields } >>> Fixes #18264 Change-Id: I9fe17ca39cf92fcdfea55064bd2eaa784ce48c88 Reviewed-on: https://go-review.googlesource.com/71990 Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org>
2017-09-12runtime: improve timers scalability on multi-CPU systemsAliaksandr Valialkin
Use per-P timers, so each P may work with its own timers. This CL improves performance on multi-CPU systems in the following cases: - When serving high number of concurrent connections with read/write deadlines set (for instance, highly loaded net/http server). - When using high number of concurrent timers. These timers may be implicitly created via context.WithDeadline or context.WithTimeout. Production servers should usually set timeout on connections and external requests in order to prevent from resource leakage. See https://blog.cloudflare.com/the-complete-guide-to-golang-net-http-timeouts/ Below are relevant benchmark results for various GOMAXPROCS values on linux/amd64: context package: name old time/op new time/op delta WithTimeout/concurrency=40 4.92µs ± 0% 5.17µs ± 1% +5.07% (p=0.000 n=9+9) WithTimeout/concurrency=4000 6.03µs ± 1% 6.49µs ± 0% +7.63% (p=0.000 n=8+10) WithTimeout/concurrency=400000 8.58µs ± 7% 9.02µs ± 4% +5.02% (p=0.019 n=10+10) name old time/op new time/op delta WithTimeout/concurrency=40-2 3.70µs ± 1% 2.78µs ± 4% -24.90% (p=0.000 n=8+9) WithTimeout/concurrency=4000-2 4.49µs ± 4% 3.67µs ± 5% -18.26% (p=0.000 n=10+10) WithTimeout/concurrency=400000-2 6.16µs ±10% 5.15µs ±13% -16.30% (p=0.000 n=10+10) name old time/op new time/op delta WithTimeout/concurrency=40-4 3.58µs ± 1% 2.64µs ± 2% -26.13% (p=0.000 n=9+10) WithTimeout/concurrency=4000-4 4.17µs ± 0% 3.32µs ± 1% -20.36% (p=0.000 n=10+10) WithTimeout/concurrency=400000-4 5.57µs ± 9% 4.83µs ±10% -13.27% (p=0.001 n=10+10) time package: name old time/op new time/op delta AfterFunc 6.15ms ± 3% 6.07ms ± 2% ~ (p=0.133 n=10+9) AfterFunc-2 3.43ms ± 1% 3.56ms ± 1% +3.91% (p=0.000 n=10+9) AfterFunc-4 5.04ms ± 2% 2.36ms ± 0% -53.20% (p=0.000 n=10+9) After 6.54ms ± 2% 6.49ms ± 3% ~ (p=0.393 n=10+10) After-2 3.68ms ± 1% 3.87ms ± 0% +5.14% (p=0.000 n=9+9) After-4 6.66ms ± 1% 2.87ms ± 1% -56.89% (p=0.000 n=10+10) Stop 698µs ± 2% 689µs ± 1% -1.26% (p=0.011 n=10+10) Stop-2 729µs ± 2% 434µs ± 3% -40.49% (p=0.000 n=10+10) Stop-4 837µs ± 3% 333µs ± 2% -60.20% (p=0.000 n=10+10) SimultaneousAfterFunc 694µs ± 1% 692µs ± 7% ~ (p=0.481 n=10+10) SimultaneousAfterFunc-2 714µs ± 3% 569µs ± 2% -20.33% (p=0.000 n=10+10) SimultaneousAfterFunc-4 782µs ± 2% 386µs ± 2% -50.67% (p=0.000 n=10+10) StartStop 267µs ± 3% 274µs ± 0% +2.64% (p=0.000 n=8+9) StartStop-2 238µs ± 2% 140µs ± 3% -40.95% (p=0.000 n=10+8) StartStop-4 320µs ± 1% 125µs ± 1% -61.02% (p=0.000 n=9+9) Reset 75.0µs ± 1% 77.5µs ± 2% +3.38% (p=0.000 n=10+10) Reset-2 150µs ± 2% 40µs ± 5% -73.09% (p=0.000 n=10+9) Reset-4 226µs ± 1% 33µs ± 1% -85.42% (p=0.000 n=10+10) Sleep 857µs ± 6% 878µs ± 9% ~ (p=0.079 n=10+9) Sleep-2 617µs ± 4% 585µs ± 2% -5.21% (p=0.000 n=10+10) Sleep-4 689µs ± 3% 465µs ± 4% -32.53% (p=0.000 n=10+10) Ticker 55.9ms ± 2% 55.9ms ± 2% ~ (p=0.971 n=10+10) Ticker-2 28.7ms ± 2% 28.1ms ± 1% -2.06% (p=0.000 n=10+10) Ticker-4 14.6ms ± 0% 13.6ms ± 1% -6.80% (p=0.000 n=9+10) Fixes #15133 Change-Id: I6f4b09d2db8c5bec93146db6501b44dbfe5c0ac4 Reviewed-on: https://go-review.googlesource.com/34784 Reviewed-by: Austin Clements <austin@google.com>
2017-04-25all: remove some unused parameters in test codeDaniel Martí
Mostly unnecessary *testing.T arguments. Found with github.com/mvdan/unparam. Change-Id: Ifb955cb88f2ce8784ee4172f4f94d860fa36ae9a Reviewed-on: https://go-review.googlesource.com/41691 Run-TryBot: Daniel Martí <mvdan@mvdan.cc> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-05-06time: deflake TestAfterQueuingBrad Fitzpatrick
Ramp up the delay on subsequent attempts. Fast builders have the same delay. Not a perfect fix, but should make it better. And this easy. Fixes #9903 maybe Fixes #10680 maybe Change-Id: I967380c2cb8196e6da9a71116961229d37b36335 Reviewed-on: https://go-review.googlesource.com/9795 Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2015-05-04time: Fix ordering of slots in AfterQueueing testKeith Randall
We shouldn't sort the slots array, as it is used each time the test is run. Tests after the first should continue to use the unsorted ordering. Note that this doesn't fix the flaky test. Just a bug I saw while investigating. Change-Id: Ic03cca637829d569d50d3a2278d19410d4dedba9 Reviewed-on: https://go-review.googlesource.com/9637 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2015-04-29time: use longer delta duration for TestAfterQueueing retriesMatthew Dempsky
The TestAfterQueueing test is inherently flaky because it relies on independent kernel threads being scheduled within the "delta" duration of each other. Normally, delta is 100ms but during "short" testing, it's reduced to 20ms. On at least OpenBSD, the CPU scheduler operates in 10ms time slices, so high system load (e.g., from running multiple Go unit tests in parallel, as happens during all.bash) can occasionally cause >20ms scheduling delays and result in test flaking. This manifests as issue 9903, which is the currently the most common OpenBSD flake. To mitigate this delay, only reduce the delta duration to 20ms for the first attempt during short testing. If this fails and the test is reattempted, subsequent attempts instead use a full 100ms delta. Fixes #9903. Change-Id: I11bdfa939e5be915f67ffad8a8aef6ed8772159a Reviewed-on: https://go-review.googlesource.com/9510 Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-03-03time: zoneinfo support for darwinDavid Crawshaw
Roll forward of 54efdc596f7b. Better testing of the build on darwin/amd64. There is still some variance between cmd/dist and the Go tool for build tag handling. Change-Id: I105669ae7f90c8c89b3839c04b182cff46be8dde Reviewed-on: https://go-review.googlesource.com/6516 Run-TryBot: David Crawshaw <crawshaw@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
2015-03-03Revert "time: zoneinfo support on darwin/arm"David Crawshaw
This reverts commit 54efdc596f7b6c711e5d65d99f1c25a0ca3628f1. Broken on darwin. Change-Id: Ic74275f36d30975263340e2b4045226eae71b16a Reviewed-on: https://go-review.googlesource.com/6514 Reviewed-by: David Crawshaw <crawshaw@golang.org>
2015-03-03time: zoneinfo support on darwin/armDavid Crawshaw
A future change will include an NSTimeZone hook so we can determine the device's current time zone. Change-Id: Ia4bd6b955e4cb720c518055541b66ff57a4dd303 Reviewed-on: https://go-review.googlesource.com/6511 Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com> Run-TryBot: David Crawshaw <crawshaw@golang.org>
2014-10-21time: panic with a more helpful error on use of invalid TimerBrad Fitzpatrick
Fixes #8721 LGTM=rsc R=r, rsc CC=golang-codereviews https://golang.org/cl/155620045
2014-09-08build: move package sources from src/pkg to srcRuss Cox
Preparation was in CL 134570043. This CL contains only the effect of 'hg mv src/pkg/* src'. For more about the move, see golang.org/s/go14nopkg.