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Fixes #38859
Change-Id: I9f4f6fa4cb529aaadfb3812e3a5c0da982a95f68
Reviewed-on: https://go-review.googlesource.com/c/go/+/633415
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
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This CL refactors sync.Mutex such that its implementation lives in the
new internal/sync package. The purpose of this change is to eventually
reverse the dependency edge between internal/concurrent and sync, such
that sync can depend on internal/concurrent (or really, its contents,
which will likely end up in internal/sync).
The only change made to the sync.Mutex code is the frame skip count for
mutex profiling, so that the internal/sync frames are omitted in the
profile.
Change-Id: Ib3603d30e8e71508c4ea883a584ae2e51ce40c3f
Reviewed-on: https://go-review.googlesource.com/c/go/+/594056
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
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The methods being implemented are part of the Locker interface,
not the RWMutex struct.
Fixes #68250.
Change-Id: I609c4d5c44e90a12914a8678971ba295519cc265
Reviewed-on: https://go-review.googlesource.com/c/go/+/595875
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
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Reviewed-by: Than McIntosh <thanm@google.com>
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The lack of links to https://go.dev/ref/mem in the sync package
documentation makes it difficult to read for people who have no previous
knowledge of that page. This PR includes the links where needed.
Fixes #67891
Change-Id: I0e1344cc6d7b702f4cb2e55fe0fcee3eb089391a
GitHub-Last-Rev: 427cf58aaeaae2e4b060248dd592e5fe8c6b7df4
GitHub-Pull-Request: golang/go#67892
Reviewed-on: https://go-review.googlesource.com/c/go/+/591395
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
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Change-Id: I9bc5fd29b0eec8ceadcfee2116de5e7524ef92c2
Reviewed-on: https://go-review.googlesource.com/c/go/+/539617
Auto-Submit: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Run-TryBot: shuang cui <imcusg@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
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Fixes #41555
Change-Id: I46b9535b1687d481d2ac76296e8ba7de26d6e2e2
Change-Id: I46b9535b1687d481d2ac76296e8ba7de26d6e2e2
GitHub-Last-Rev: 38af46c18922eea80e05c8ed9f5e10002ab7244d
GitHub-Pull-Request: golang/go#61977
Reviewed-on: https://go-review.googlesource.com/c/go/+/518859
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Bryan Mills <bcmills@google.com>
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Fixes #23558
Fixes #54162
Change-Id: I3cf6efe466080cdb17e171218e9385ccb272c301
Reviewed-on: https://go-review.googlesource.com/c/go/+/421441
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
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This change adds 3 new waitReasons that correspond to sync.Mutex.Lock,
sync.RWMutex.RLock, and sync.RWMutex.Lock that are plumbed down into
semacquire1 by exporting new functions to the sync package from the
runtime.
Currently these three functions show up as "semacquire" in backtraces
which isn't very clear, though the stack trace itself should reveal
what's really going on. This represents a minor improvement to backtrace
readability, though blocking on an RWMutex.w.Lock will still show up as
blocking on a regular mutex (I suppose technically it is).
This is a step toward helping the runtime identify when a goroutine is
blocked on a mutex of some kind.
For #49881.
Change-Id: Ia409b4d27e117fe4bfdc25fa541e9c58d6d587b9
Reviewed-on: https://go-review.googlesource.com/c/go/+/427616
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
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Change-Id: I7fd9c0636cd00891f5cdf36c0f68f897772042f2
Reviewed-on: https://go-review.googlesource.com/c/go/+/429767
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
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A few of these are copied from the memory model doc.
Many are entirely new, following discussion on #47141.
See https://research.swtch.com/gomm for background.
The rule we are establishing is that each type that is meant
to help synchronize a Go program should document its
happens-before guarantees.
For #50859.
Change-Id: I947c40639b263abe67499fa74f68711a97873a39
Reviewed-on: https://go-review.googlesource.com/c/go/+/381316
Auto-Submit: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>
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"User" throws are throws due to some invariant broken by the application.
"System" throws are due to some invariant broken by the runtime,
environment, etc (i.e., not the fault of the application).
This CL sends "user" throws through the new fatal. Currently this
function is identical to throw, but with a different name to clearly
differentiate the throw type in the stack trace, and hopefully be a bit
more clear to users what it means.
This CL changes a few categories of throw to fatal:
1. Concurrent map read/write.
2. Deadlock detection.
3. Unlock of unlocked sync.Mutex.
4. Inconsistent results from syscall.AllThreadsSyscall.
"Thread exhaustion" and "out of memory" (usually address space full)
throws are additional throws that are arguably the fault of user code,
but I've left off for now because there is no specific invariant that
they have broken to get into these states.
For #51485
Change-Id: I713276a6c290fd34a6563e6e9ef378669d74ae32
Reviewed-on: https://go-review.googlesource.com/c/go/+/390420
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>
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Use of these functions is almost (but not) always a bad idea.
Very rarely they are necessary, and third-party implementations
(using a mutex and an atomic word, say) cannot integrate as well
with the race detector as implmentations in package sync itself.
Fixes #45435.
Change-Id: I0128ca48ef5e0a3b09c913f0f3a7ee5c56388000
Reviewed-on: https://go-review.googlesource.com/c/go/+/319769
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
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RWMutex provides explicit acquire/release synchronization events to the
race detector to model the mutex. It disables sync events within the
methods to avoid e.g., the atomics from adding false synchronization
events, which could cause false negatives in the race detector.
Change-Id: I5126ce2efaab151811ac264864aab1fa025a4aaf
Reviewed-on: https://go-review.googlesource.com/c/go/+/270865
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Trust: Michael Pratt <mpratt@google.com>
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RWMutex.RLock is already inlineable, so add a test for it as well.
name old time/op new time/op delta
RWMutexUncontended 66.5ns ± 0% 60.3ns ± 1% -9.38% (p=0.000 n=12+20)
RWMutexUncontended-4 16.7ns ± 0% 15.3ns ± 1% -8.49% (p=0.000 n=17+20)
RWMutexUncontended-16 7.86ns ± 0% 7.69ns ± 0% -2.08% (p=0.000 n=18+15)
RWMutexWrite100 25.1ns ± 0% 24.0ns ± 1% -4.28% (p=0.000 n=20+18)
RWMutexWrite100-4 46.7ns ± 5% 44.1ns ± 4% -5.53% (p=0.000 n=20+20)
RWMutexWrite100-16 68.3ns ±11% 65.7ns ± 8% -3.81% (p=0.003 n=20+20)
RWMutexWrite10 26.7ns ± 1% 25.7ns ± 0% -3.75% (p=0.000 n=17+14)
RWMutexWrite10-4 34.9ns ± 2% 33.8ns ± 2% -3.15% (p=0.000 n=20+20)
RWMutexWrite10-16 37.4ns ± 2% 36.1ns ± 2% -3.51% (p=0.000 n=18+20)
RWMutexWorkWrite100 163ns ± 0% 162ns ± 0% -0.89% (p=0.000 n=18+20)
RWMutexWorkWrite100-4 189ns ± 4% 184ns ± 4% -2.89% (p=0.000 n=19+20)
RWMutexWorkWrite100-16 207ns ± 4% 200ns ± 2% -3.07% (p=0.000 n=19+20)
RWMutexWorkWrite10 153ns ± 0% 151ns ± 1% -0.75% (p=0.000 n=20+20)
RWMutexWorkWrite10-4 177ns ± 1% 176ns ± 2% -0.63% (p=0.004 n=17+20)
RWMutexWorkWrite10-16 191ns ± 2% 189ns ± 1% -0.83% (p=0.015 n=20+17)
linux/amd64 bin/go 14688201 (previous commit 14675861, +12340/+0.08%)
The cumulative effect of this and the previous 3 commits is:
name old time/op new time/op delta
MutexUncontended 19.3ns ± 1% 16.4ns ± 1% -15.13% (p=0.000 n=20+20)
MutexUncontended-4 5.24ns ± 0% 4.09ns ± 0% -21.95% (p=0.000 n=20+18)
MutexUncontended-16 2.10ns ± 0% 2.12ns ± 0% +0.95% (p=0.000 n=15+17)
Mutex 19.6ns ± 0% 16.3ns ± 1% -17.12% (p=0.000 n=20+20)
Mutex-4 54.6ns ± 5% 45.6ns ±10% -16.51% (p=0.000 n=20+19)
Mutex-16 133ns ± 5% 130ns ± 3% -1.99% (p=0.002 n=20+20)
MutexSlack 33.4ns ± 2% 16.2ns ± 0% -51.44% (p=0.000 n=19+20)
MutexSlack-4 206ns ± 5% 209ns ± 9% ~ (p=0.154 n=20+20)
MutexSlack-16 89.4ns ± 1% 90.9ns ± 2% +1.70% (p=0.000 n=18+17)
MutexWork 60.5ns ± 0% 55.3ns ± 1% -8.59% (p=0.000 n=12+20)
MutexWork-4 105ns ± 5% 97ns ±11% -7.95% (p=0.000 n=20+20)
MutexWork-16 157ns ± 1% 158ns ± 1% +0.66% (p=0.001 n=18+17)
MutexWorkSlack 70.2ns ± 5% 55.3ns ± 0% -21.30% (p=0.000 n=19+18)
MutexWorkSlack-4 277ns ±13% 260ns ±15% -6.35% (p=0.002 n=20+18)
MutexWorkSlack-16 156ns ± 0% 146ns ± 1% -6.40% (p=0.000 n=16+19)
MutexNoSpin 966ns ± 0% 976ns ± 1% +0.97% (p=0.000 n=15+17)
MutexNoSpin-4 269ns ± 4% 272ns ± 4% +1.15% (p=0.048 n=20+18)
MutexNoSpin-16 122ns ± 0% 119ns ± 1% -2.63% (p=0.000 n=19+15)
MutexSpin 3.13µs ± 0% 3.12µs ± 0% -0.17% (p=0.000 n=18+18)
MutexSpin-4 826ns ± 1% 833ns ± 1% +0.84% (p=0.000 n=19+17)
MutexSpin-16 397ns ± 1% 394ns ± 1% -0.78% (p=0.000 n=19+19)
Once 5.67ns ± 0% 2.07ns ± 2% -63.43% (p=0.000 n=20+20)
Once-4 1.47ns ± 2% 0.54ns ± 3% -63.49% (p=0.000 n=19+20)
Once-16 0.58ns ± 0% 0.17ns ± 5% -70.49% (p=0.000 n=17+17)
RWMutexUncontended 71.4ns ± 0% 60.3ns ± 1% -15.60% (p=0.000 n=16+20)
RWMutexUncontended-4 18.4ns ± 4% 15.3ns ± 1% -17.14% (p=0.000 n=20+20)
RWMutexUncontended-16 8.01ns ± 0% 7.69ns ± 0% -3.91% (p=0.000 n=18+15)
RWMutexWrite100 24.9ns ± 0% 24.0ns ± 1% -3.57% (p=0.000 n=19+18)
RWMutexWrite100-4 46.5ns ± 3% 44.1ns ± 4% -5.09% (p=0.000 n=17+20)
RWMutexWrite100-16 68.9ns ± 3% 65.7ns ± 8% -4.65% (p=0.000 n=18+20)
RWMutexWrite10 27.1ns ± 0% 25.7ns ± 0% -5.25% (p=0.000 n=17+14)
RWMutexWrite10-4 34.8ns ± 1% 33.8ns ± 2% -2.96% (p=0.000 n=20+20)
RWMutexWrite10-16 37.5ns ± 2% 36.1ns ± 2% -3.72% (p=0.000 n=20+20)
RWMutexWorkWrite100 164ns ± 0% 162ns ± 0% -1.49% (p=0.000 n=12+20)
RWMutexWorkWrite100-4 186ns ± 3% 184ns ± 4% ~ (p=0.097 n=20+20)
RWMutexWorkWrite100-16 204ns ± 2% 200ns ± 2% -1.58% (p=0.000 n=18+20)
RWMutexWorkWrite10 153ns ± 0% 151ns ± 1% -1.21% (p=0.000 n=20+20)
RWMutexWorkWrite10-4 179ns ± 1% 176ns ± 2% -1.25% (p=0.000 n=19+20)
RWMutexWorkWrite10-16 191ns ± 1% 189ns ± 1% -0.94% (p=0.000 n=15+17)
Change-Id: I9269bf2ac42a04c610624f707d3268dcb17390f8
Reviewed-on: https://go-review.googlesource.com/c/go/+/152698
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
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name old time/op new time/op delta
MutexUncontended 18.9ns ± 0% 16.2ns ± 0% -14.29% (p=0.000 n=19+19)
MutexUncontended-4 4.75ns ± 1% 4.08ns ± 0% -14.20% (p=0.000 n=20+19)
MutexUncontended-16 2.05ns ± 0% 2.11ns ± 0% +2.93% (p=0.000 n=19+16)
Mutex 19.3ns ± 1% 16.2ns ± 0% -15.86% (p=0.000 n=17+19)
Mutex-4 52.4ns ± 4% 48.6ns ± 9% -7.22% (p=0.000 n=20+20)
Mutex-16 139ns ± 2% 140ns ± 3% +1.03% (p=0.011 n=16+20)
MutexSlack 18.9ns ± 1% 16.2ns ± 1% -13.96% (p=0.000 n=20+20)
MutexSlack-4 225ns ± 8% 211ns ±10% -5.94% (p=0.000 n=18+19)
MutexSlack-16 98.4ns ± 1% 90.9ns ± 1% -7.60% (p=0.000 n=17+18)
MutexWork 58.2ns ± 3% 55.4ns ± 0% -4.82% (p=0.000 n=20+17)
MutexWork-4 103ns ± 7% 95ns ±18% -8.03% (p=0.000 n=20+20)
MutexWork-16 163ns ± 2% 155ns ± 2% -4.47% (p=0.000 n=18+18)
MutexWorkSlack 57.7ns ± 1% 55.4ns ± 0% -3.99% (p=0.000 n=20+13)
MutexWorkSlack-4 276ns ±13% 260ns ±10% -5.64% (p=0.001 n=19+19)
MutexWorkSlack-16 147ns ± 0% 156ns ± 1% +5.87% (p=0.000 n=14+19)
MutexNoSpin 968ns ± 0% 900ns ± 1% -6.98% (p=0.000 n=20+18)
MutexNoSpin-4 270ns ± 2% 255ns ± 2% -5.74% (p=0.000 n=19+20)
MutexNoSpin-16 120ns ± 4% 112ns ± 0% -6.99% (p=0.000 n=19+14)
MutexSpin 3.13µs ± 1% 3.19µs ± 6% ~ (p=0.401 n=20+20)
MutexSpin-4 832ns ± 2% 831ns ± 1% -0.17% (p=0.023 n=16+18)
MutexSpin-16 395ns ± 0% 399ns ± 0% +0.94% (p=0.000 n=17+19)
RWMutexUncontended 69.5ns ± 0% 68.4ns ± 0% -1.59% (p=0.000 n=20+20)
RWMutexUncontended-4 17.5ns ± 0% 16.7ns ± 0% -4.30% (p=0.000 n=18+17)
RWMutexUncontended-16 7.92ns ± 0% 7.87ns ± 0% -0.61% (p=0.000 n=18+17)
RWMutexWrite100 24.9ns ± 1% 25.0ns ± 1% +0.32% (p=0.000 n=20+20)
RWMutexWrite100-4 46.2ns ± 4% 46.2ns ± 5% ~ (p=0.840 n=19+20)
RWMutexWrite100-16 69.9ns ± 5% 69.9ns ± 3% ~ (p=0.545 n=20+19)
RWMutexWrite10 27.0ns ± 2% 26.8ns ± 2% -0.98% (p=0.001 n=20+20)
RWMutexWrite10-4 34.7ns ± 2% 35.0ns ± 4% ~ (p=0.191 n=18+20)
RWMutexWrite10-16 37.2ns ± 4% 37.3ns ± 2% ~ (p=0.438 n=20+19)
RWMutexWorkWrite100 164ns ± 0% 163ns ± 0% -0.24% (p=0.025 n=20+20)
RWMutexWorkWrite100-4 193ns ± 3% 191ns ± 2% -1.06% (p=0.027 n=20+20)
RWMutexWorkWrite100-16 210ns ± 3% 207ns ± 3% -1.22% (p=0.038 n=20+20)
RWMutexWorkWrite10 153ns ± 0% 153ns ± 0% ~ (all equal)
RWMutexWorkWrite10-4 178ns ± 2% 179ns ± 2% ~ (p=0.186 n=20+20)
RWMutexWorkWrite10-16 192ns ± 2% 192ns ± 2% ~ (p=0.731 n=19+20)
linux/amd64 bin/go 14663387 (previous commit 14630572, +32815/+0.22%)
Change-Id: I98171006dce14069b1a62da07c3d165455a7906b
Reviewed-on: https://go-review.googlesource.com/c/go/+/148959
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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Make use of the newly-enabled limited midstack inlining.
Similar changes will be done in followup CLs.
name old time/op new time/op delta
MutexUncontended 19.3ns ± 1% 18.9ns ± 0% -1.92% (p=0.000 n=20+19)
MutexUncontended-4 5.24ns ± 0% 4.75ns ± 1% -9.25% (p=0.000 n=20+20)
MutexUncontended-16 2.10ns ± 0% 2.05ns ± 0% -2.38% (p=0.000 n=15+19)
Mutex 19.6ns ± 0% 19.3ns ± 1% -1.92% (p=0.000 n=20+17)
Mutex-4 54.6ns ± 5% 52.4ns ± 4% -4.09% (p=0.000 n=20+20)
Mutex-16 133ns ± 5% 139ns ± 2% +4.23% (p=0.000 n=20+16)
MutexSlack 33.4ns ± 2% 18.9ns ± 1% -43.56% (p=0.000 n=19+20)
MutexSlack-4 206ns ± 5% 225ns ± 8% +9.12% (p=0.000 n=20+18)
MutexSlack-16 89.4ns ± 1% 98.4ns ± 1% +10.10% (p=0.000 n=18+17)
MutexWork 60.5ns ± 0% 58.2ns ± 3% -3.75% (p=0.000 n=12+20)
MutexWork-4 105ns ± 5% 103ns ± 7% -1.68% (p=0.007 n=20+20)
MutexWork-16 157ns ± 1% 163ns ± 2% +3.90% (p=0.000 n=18+18)
MutexWorkSlack 70.2ns ± 5% 57.7ns ± 1% -17.81% (p=0.000 n=19+20)
MutexWorkSlack-4 277ns ±13% 276ns ±13% ~ (p=0.682 n=20+19)
MutexWorkSlack-16 156ns ± 0% 147ns ± 0% -5.62% (p=0.000 n=16+14)
MutexNoSpin 966ns ± 0% 968ns ± 0% +0.11% (p=0.029 n=15+20)
MutexNoSpin-4 269ns ± 4% 270ns ± 2% ~ (p=0.807 n=20+19)
MutexNoSpin-16 122ns ± 0% 120ns ± 4% -1.63% (p=0.000 n=19+19)
MutexSpin 3.13µs ± 0% 3.13µs ± 1% +0.16% (p=0.004 n=18+20)
MutexSpin-4 826ns ± 1% 832ns ± 2% +0.74% (p=0.000 n=19+16)
MutexSpin-16 397ns ± 1% 395ns ± 0% -0.50% (p=0.000 n=19+17)
RWMutexUncontended 71.4ns ± 0% 69.5ns ± 0% -2.72% (p=0.000 n=16+20)
RWMutexUncontended-4 18.4ns ± 4% 17.5ns ± 0% -4.92% (p=0.000 n=20+18)
RWMutexUncontended-16 8.01ns ± 0% 7.92ns ± 0% -1.15% (p=0.000 n=18+18)
RWMutexWrite100 24.9ns ± 0% 24.9ns ± 1% ~ (p=0.099 n=19+20)
RWMutexWrite100-4 46.5ns ± 3% 46.2ns ± 4% ~ (p=0.253 n=17+19)
RWMutexWrite100-16 68.9ns ± 3% 69.9ns ± 5% +1.46% (p=0.012 n=18+20)
RWMutexWrite10 27.1ns ± 0% 27.0ns ± 2% ~ (p=0.128 n=17+20)
RWMutexWrite10-4 34.8ns ± 1% 34.7ns ± 2% ~ (p=0.180 n=20+18)
RWMutexWrite10-16 37.5ns ± 2% 37.2ns ± 4% -0.89% (p=0.023 n=20+20)
RWMutexWorkWrite100 164ns ± 0% 164ns ± 0% ~ (p=0.106 n=12+20)
RWMutexWorkWrite100-4 186ns ± 3% 193ns ± 3% +3.46% (p=0.000 n=20+20)
RWMutexWorkWrite100-16 204ns ± 2% 210ns ± 3% +2.96% (p=0.000 n=18+20)
RWMutexWorkWrite10 153ns ± 0% 153ns ± 0% -0.20% (p=0.017 n=20+19)
RWMutexWorkWrite10-4 179ns ± 1% 178ns ± 2% ~ (p=0.215 n=19+20)
RWMutexWorkWrite10-16 191ns ± 1% 192ns ± 2% ~ (p=0.166 n=15+19)
linux/amd64 bin/go 14630572 (previous commit 14605947, +24625/+0.17%)
Change-Id: I3f9d1765801fe0b8deb1bc2728b8bba8a7508e23
Reviewed-on: https://go-review.googlesource.com/c/go/+/148958
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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Remove unnecessary race.Release annotation from Unlock.
For RWMutex we want to establish the following happens-before (HB) edges:
1. Between Unlock and the subsequent Lock.
2. Between Unlock and the subsequent RLock.
3. Between batch of RUnlock's and the subsequent Lock.
1 is provided by Release(&rw.readerSem) in Unlock and Acquire(&rw.readerSem) in Lock.
2 is provided by Release(&rw.readerSem) in Unlock and Acquire(&rw.readerSem) in RLock.
3 is provided by ReleaseMerge(&rw.writerSem) in RUnlock in Acquire(&rw.writerSem) in Lock,
since we want to establish HB between a batch of RUnlock's this uses ReleaseMerge instead of Release.
Release(&rw.writerSem) in Unlock is simply not needed.
FWIW this is also how C++ tsan handles mutexes, not a proof but at least something.
Making 2 implementations consistent also simplifies any kind of reasoning against both of them.
Since this only affects performance, a reasonable test is not possible.
Everything should just continue to work but slightly faster.
Credit for discovering this goes to Jamie Liu.
Change-Id: Ice37d29ecb7a5faed3f7781c38dd32c7469b2735
Reviewed-on: https://go-review.googlesource.com/120495
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
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Include reader / writer interactions of RWMutex in the mutex profile.
Writer contention is already included in the profile, since a plain Mutex
is used to control exclusion.
Fixes #18496
Change-Id: Ib0dc1ffa0fd5e6d964a6f7764d7f09556eb63f00
Reviewed-on: https://go-review.googlesource.com/87095
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Peter Weinberger <pjw@google.com>
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We used a mix of both before.
I've never heard anybody say "an arr-double you mutex" when speaking.
Fixes #23457
Change-Id: I802b5eb2339f885ca9d24607eeda565763165298
Reviewed-on: https://go-review.googlesource.com/87896
Reviewed-by: Andrew Bonventre <andybons@golang.org>
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This is a runtime version of sync.RWMutex that can be used by code in
the runtime package. The type is not quite the same, in that the zero
value is not valid.
For future use by CL 43713.
Updates #19546
Change-Id: I431eb3688add16ce1274dab97285f555b72735bf
Reviewed-on: https://go-review.googlesource.com/45991
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
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Updates #15418 (the original bug, fixed by https://golang.org/cl/23570)
Fixes #19460 (round two)
Change-Id: Iac4447daabb56e3b470046c489c22d588c20163e
Reviewed-on: https://go-review.googlesource.com/45697
Reviewed-by: Ian Lance Taylor <iant@golang.org>
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Remove note that sync.Cond, sync.Mutex, sync.RWMutex and atomic.Value
can be created as part of other data structures. Structs can be embedded
by default, and default should not be repeated.
Fixes #20471.
Change-Id: If3f5703d3f60abd96482b58ca43450d02a9e645a
Reviewed-on: https://go-review.googlesource.com/44071
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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Add new starvation mode for Mutex.
In starvation mode ownership is directly handed off from
unlocking goroutine to the next waiter. New arriving goroutines
don't compete for ownership.
Unfair wait time is now limited to 1ms.
Also fix a long standing bug that goroutines were requeued
at the tail of the wait queue. That lead to even more unfair
acquisition times with multiple waiters.
Performance of normal mode is not considerably affected.
Fixes #13086
On the provided in the issue lockskew program:
done in 1.207853ms
done in 1.177451ms
done in 1.184168ms
done in 1.198633ms
done in 1.185797ms
done in 1.182502ms
done in 1.316485ms
done in 1.211611ms
done in 1.182418ms
name old time/op new time/op delta
MutexUncontended-48 0.65ns ± 0% 0.65ns ± 1% ~ (p=0.087 n=10+10)
Mutex-48 112ns ± 1% 114ns ± 1% +1.69% (p=0.000 n=10+10)
MutexSlack-48 113ns ± 0% 87ns ± 1% -22.65% (p=0.000 n=8+10)
MutexWork-48 149ns ± 0% 145ns ± 0% -2.48% (p=0.000 n=9+10)
MutexWorkSlack-48 149ns ± 0% 122ns ± 3% -18.26% (p=0.000 n=6+10)
MutexNoSpin-48 103ns ± 4% 105ns ± 3% ~ (p=0.089 n=10+10)
MutexSpin-48 490ns ± 4% 515ns ± 6% +5.08% (p=0.006 n=10+10)
Cond32-48 13.4µs ± 6% 13.1µs ± 5% -2.75% (p=0.023 n=10+10)
RWMutexWrite100-48 53.2ns ± 3% 41.2ns ± 3% -22.57% (p=0.000 n=10+10)
RWMutexWrite10-48 45.9ns ± 2% 43.9ns ± 2% -4.38% (p=0.000 n=10+10)
RWMutexWorkWrite100-48 122ns ± 2% 134ns ± 1% +9.92% (p=0.000 n=10+10)
RWMutexWorkWrite10-48 206ns ± 1% 188ns ± 1% -8.52% (p=0.000 n=8+10)
Cond32-24 12.1µs ± 3% 12.4µs ± 3% +1.98% (p=0.043 n=10+9)
MutexUncontended-24 0.74ns ± 1% 0.75ns ± 1% ~ (p=0.650 n=10+10)
Mutex-24 122ns ± 2% 124ns ± 1% +1.31% (p=0.007 n=10+10)
MutexSlack-24 96.9ns ± 2% 102.8ns ± 2% +6.11% (p=0.000 n=10+10)
MutexWork-24 146ns ± 1% 135ns ± 2% -7.70% (p=0.000 n=10+9)
MutexWorkSlack-24 135ns ± 1% 128ns ± 2% -5.01% (p=0.000 n=10+9)
MutexNoSpin-24 114ns ± 3% 110ns ± 4% -3.84% (p=0.000 n=10+10)
MutexSpin-24 482ns ± 4% 475ns ± 8% ~ (p=0.286 n=10+10)
RWMutexWrite100-24 43.0ns ± 3% 43.1ns ± 2% ~ (p=0.956 n=10+10)
RWMutexWrite10-24 43.4ns ± 1% 43.2ns ± 1% ~ (p=0.085 n=10+9)
RWMutexWorkWrite100-24 130ns ± 3% 131ns ± 3% ~ (p=0.747 n=10+10)
RWMutexWorkWrite10-24 191ns ± 1% 192ns ± 1% ~ (p=0.210 n=10+10)
Cond32-12 11.5µs ± 2% 11.7µs ± 2% +1.98% (p=0.002 n=10+10)
MutexUncontended-12 1.48ns ± 0% 1.50ns ± 1% +1.08% (p=0.004 n=10+10)
Mutex-12 141ns ± 1% 143ns ± 1% +1.63% (p=0.000 n=10+10)
MutexSlack-12 121ns ± 0% 119ns ± 0% -1.65% (p=0.001 n=8+9)
MutexWork-12 141ns ± 2% 150ns ± 3% +6.36% (p=0.000 n=9+10)
MutexWorkSlack-12 131ns ± 0% 138ns ± 0% +5.73% (p=0.000 n=9+10)
MutexNoSpin-12 87.0ns ± 1% 83.7ns ± 1% -3.80% (p=0.000 n=10+10)
MutexSpin-12 364ns ± 1% 377ns ± 1% +3.77% (p=0.000 n=10+10)
RWMutexWrite100-12 42.8ns ± 1% 43.9ns ± 1% +2.41% (p=0.000 n=8+10)
RWMutexWrite10-12 39.8ns ± 4% 39.3ns ± 1% ~ (p=0.433 n=10+9)
RWMutexWorkWrite100-12 131ns ± 1% 131ns ± 0% ~ (p=0.591 n=10+9)
RWMutexWorkWrite10-12 173ns ± 1% 174ns ± 0% ~ (p=0.059 n=10+8)
Cond32-6 10.9µs ± 2% 10.9µs ± 2% ~ (p=0.739 n=10+10)
MutexUncontended-6 2.97ns ± 0% 2.97ns ± 0% ~ (all samples are equal)
Mutex-6 122ns ± 6% 122ns ± 2% ~ (p=0.668 n=10+10)
MutexSlack-6 149ns ± 3% 142ns ± 3% -4.63% (p=0.000 n=10+10)
MutexWork-6 136ns ± 3% 140ns ± 5% ~ (p=0.077 n=10+10)
MutexWorkSlack-6 152ns ± 0% 138ns ± 2% -9.21% (p=0.000 n=6+10)
MutexNoSpin-6 150ns ± 1% 152ns ± 0% +1.50% (p=0.000 n=8+10)
MutexSpin-6 726ns ± 0% 730ns ± 1% ~ (p=0.069 n=10+10)
RWMutexWrite100-6 40.6ns ± 1% 40.9ns ± 1% +0.91% (p=0.001 n=8+10)
RWMutexWrite10-6 37.1ns ± 0% 37.0ns ± 1% ~ (p=0.386 n=9+10)
RWMutexWorkWrite100-6 133ns ± 1% 134ns ± 1% +1.01% (p=0.005 n=9+10)
RWMutexWorkWrite10-6 152ns ± 0% 152ns ± 0% ~ (all samples are equal)
Cond32-2 7.86µs ± 2% 7.95µs ± 2% +1.10% (p=0.023 n=10+10)
MutexUncontended-2 8.10ns ± 0% 9.11ns ± 4% +12.44% (p=0.000 n=9+10)
Mutex-2 32.9ns ± 9% 38.4ns ± 6% +16.58% (p=0.000 n=10+10)
MutexSlack-2 93.4ns ± 1% 98.5ns ± 2% +5.39% (p=0.000 n=10+9)
MutexWork-2 40.8ns ± 3% 43.8ns ± 7% +7.38% (p=0.000 n=10+9)
MutexWorkSlack-2 98.6ns ± 5% 108.2ns ± 2% +9.80% (p=0.000 n=10+8)
MutexNoSpin-2 399ns ± 1% 398ns ± 2% ~ (p=0.463 n=8+9)
MutexSpin-2 1.99µs ± 3% 1.97µs ± 1% -0.81% (p=0.003 n=9+8)
RWMutexWrite100-2 37.6ns ± 5% 46.0ns ± 4% +22.17% (p=0.000 n=10+8)
RWMutexWrite10-2 50.1ns ± 6% 36.8ns ±12% -26.46% (p=0.000 n=9+10)
RWMutexWorkWrite100-2 136ns ± 0% 134ns ± 2% -1.80% (p=0.001 n=7+9)
RWMutexWorkWrite10-2 140ns ± 1% 138ns ± 1% -1.50% (p=0.000 n=10+10)
Cond32 5.93µs ± 1% 5.91µs ± 0% ~ (p=0.411 n=9+10)
MutexUncontended 15.9ns ± 0% 15.8ns ± 0% -0.63% (p=0.000 n=8+8)
Mutex 15.9ns ± 0% 15.8ns ± 0% -0.44% (p=0.003 n=10+10)
MutexSlack 26.9ns ± 3% 26.7ns ± 2% ~ (p=0.084 n=10+10)
MutexWork 47.8ns ± 0% 47.9ns ± 0% +0.21% (p=0.014 n=9+8)
MutexWorkSlack 54.9ns ± 3% 54.5ns ± 3% ~ (p=0.254 n=10+10)
MutexNoSpin 786ns ± 2% 765ns ± 1% -2.66% (p=0.000 n=10+10)
MutexSpin 3.87µs ± 1% 3.83µs ± 0% -0.85% (p=0.005 n=9+8)
RWMutexWrite100 21.2ns ± 2% 21.0ns ± 1% -0.88% (p=0.018 n=10+9)
RWMutexWrite10 22.6ns ± 1% 22.6ns ± 0% ~ (p=0.471 n=9+9)
RWMutexWorkWrite100 132ns ± 0% 132ns ± 0% ~ (all samples are equal)
RWMutexWorkWrite10 124ns ± 0% 123ns ± 0% ~ (p=0.656 n=10+10)
Change-Id: I66412a3a0980df1233ad7a5a0cd9723b4274528b
Reviewed-on: https://go-review.googlesource.com/34310
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
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The panic leaves the lock in an unusable state.
Trying to panic with a usable state makes the lock significantly
less efficient and scalable (see early CL patch sets and discussion).
Instead, use runtime.throw, which will crash the program directly.
In general throw is reserved for when the runtime detects truly
serious, unrecoverable problems. This problem is certainly serious,
and, without a significant performance hit, is unrecoverable.
Fixes #13879.
Change-Id: I41920d9e2317270c6f909957d195bd8b68177f8d
Reviewed-on: https://go-review.googlesource.com/31359
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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Fixes #15418
Change-Id: Ibc51d602eb28819d0e44e5ca13a5c61573e4111c
Reviewed-on: https://go-review.googlesource.com/23570
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
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Embed noLock struct into the following types, so `go vet -copylocks` catches
their copying additionally to types containing sync.Mutex:
- sync.Cond
- sync.WaitGroup
- sync.Pool
- atomic.Value
Fixes #14582
Change-Id: Icb543ef5ad10524ad239a15eec8a9b334b0e0660
Reviewed-on: https://go-review.googlesource.com/22015
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
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The tree's pretty inconsistent about single space vs double space
after a period in documentation. Make it consistently a single space,
per earlier decisions. This means contributors won't be confused by
misleading precedence.
This CL doesn't use go/doc to parse. It only addresses // comments.
It was generated with:
$ perl -i -npe 's,^(\s*// .+[a-z]\.) +([A-Z]),$1 $2,' $(git grep -l -E '^\s*//(.+\.) +([A-Z])')
$ go test go/doc -update
Change-Id: Iccdb99c37c797ef1f804a94b22ba5ee4b500c4f7
Reviewed-on: https://go-review.googlesource.com/20022
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Dave Day <djd@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
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Factor out duplicated race thunks from sync, syscall net
and fmt packages into a separate package and use it.
Fixes #8593
Change-Id: I156869c50946277809f6b509463752e7f7d28cdb
Reviewed-on: https://go-review.googlesource.com/14870
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
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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.
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