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| author | Michael Anthony Knyszek <mknyszek@google.com> | 2025-08-19 19:29:55 +0000 |
|---|---|---|
| committer | Gopher Robot <gobot@golang.org> | 2025-08-19 13:39:08 -0700 |
| commit | ffa882059cfbfc7cd5f16c83d24775c08d63668f (patch) | |
| tree | 72a14688df1f38ad04d0e7bcf6d6aae0ae31af5c | |
| parent | 1f2e8e03e48597367e674138e26432345c685b1c (diff) | |
| download | go-ffa882059cfbfc7cd5f16c83d24775c08d63668f.tar.xz | |
unique: deflake TestCanonMap/LoadOrStore/ConcurrentUnsharedKeys
I do not know yet what's causing this flake, but I've debugged it enough
to be confident that it's not a serious issue; it seems to be a test
flake. There is some path through which the tree nodes or keys might
still be transiently reachable, but I don't yet know what that is.
Details about what I tried and ruled out are in the code.
For #74083.
Change-Id: I97cdaf3f97e8c543fcc2ccde8b7e682893ae2f97
Reviewed-on: https://go-review.googlesource.com/c/go/+/697341
Auto-Submit: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
| -rw-r--r-- | src/unique/canonmap_test.go | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/src/unique/canonmap_test.go b/src/unique/canonmap_test.go index e8f56d8e00..9609d7d422 100644 --- a/src/unique/canonmap_test.go +++ b/src/unique/canonmap_test.go @@ -108,6 +108,25 @@ func testCanonMap(t *testing.T, newMap func() *canonMap[string]) { wg.Wait() } + // Run an extra GC cycle to de-flake. Sometimes the cleanups + // fail to run in time, despite drainCleanupQueue. + // + // TODO(mknyszek): Figure out why the extra GC is necessary, + // and what is transiently keeping the cleanups live. + // * I have confirmed that they are not completely stuck, and + // they always eventually run. + // * I have also confirmed it's not asynchronous preemption + // keeping them around (though that is a possibility). + // * I have confirmed that they are not simply sitting on + // the queue, and that drainCleanupQueue is just failing + // to actually empty the queue. + // * I have confirmed that it's not a write barrier that's + // keeping it alive, nor is it a weak pointer dereference + // (which shades the object during the GC). + // The corresponding objects do seem to be transiently truly + // reachable, but I have no idea by what path. + runtime.GC() + // Drain cleanups so everything is deleted. drainCleanupQueue(t) |