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>
Fixes#66215
Change-Id: Id7de15feabe08f66c048dc114c09494813c9febc
Reviewed-on: https://go-review.googlesource.com/c/go/+/570695
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
A few recent godebugs are missing IncNonDefault uses.
Test for that, so that people remember to do it.
Filed bugs for the missing ones.
For #66215.
For #66216.
For #66217.
Change-Id: Ia3fd10fd108e1b003bb30a8bc2f83995c768fab6
Reviewed-on: https://go-review.googlesource.com/c/go/+/570275
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Damien Neil <dneil@google.com>
This CL updates os.Readlink so it no longer tries to normalize volumes
to drive letters, which was not always even possible.
This behavior is controlled by the `winreadlinkvolume` setting.
For Go 1.23, it defaults to `winreadlinkvolume=1`.
Previous versions default to `winreadlinkvolume=0`.
Fixes#63703.
Cq-Include-Trybots: luci.golang.try:gotip-windows-amd64-longtest,gotip-windows-arm64
Change-Id: Icd6fabbc8f0b78e23a82eef8db89940e89e9222d
Reviewed-on: https://go-review.googlesource.com/c/go/+/567735
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This CL changes the behavior of os.Lstat to stop setting the
os.ModeSymlink type mode bit for mount points on Windows. As a result,
filepath.EvalSymlinks no longer evaluates mount points, which was the
cause of many inconsistencies and bugs.
Additionally, os.Lstat starts setting the os.ModeIrregular type mode bit
for all reparse tags on Windows, except for those that are explicitly
supported by the os package, which, since this CL, doesn't include mount
points. This helps to identify files that need special handling outside
of the os package.
This behavior is controlled by the `winsymlink` GODEBUG setting.
For Go 1.23, it defaults to `winsymlink=1`.
Previous versions default to `winsymlink=0`.
Fixes#39786Fixes#40176Fixes#61893
Updates #63703
Updates #40180
Updates #63429
Cq-Include-Trybots: luci.golang.try:gotip-windows-amd64-longtest,gotip-windows-arm64
Change-Id: I2e7372ab8862f5062667d30db6958d972bce5407
Reviewed-on: https://go-review.googlesource.com/c/go/+/565136
Reviewed-by: Bryan Mills <bcmills@google.com>
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Reviewed-by: Michael Knyszek <mknyszek@google.com>
This reverts CL 542699.
Reason for revert: Some applications assume FindProcess does not return
errors.
For #62654.
Fixes#65866.
Change-Id: Ic185a6253c8e508b08150b618c39a9905f6cdd60
Reviewed-on: https://go-review.googlesource.com/c/go/+/566476
Reviewed-by: Bryan Mills <bcmills@google.com>
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Auto-Submit: Michael Pratt <mpratt@google.com>
Amend FindProcess to use pidfdFind, and make it return ErrProcessDone
if pidfdFind is used and the process is not found.
Since this is a change in API, introduce GODEBUG osfinderr=0 setting
to disable the feature.
Change-Id: I724c6f622f0c99f21a70b864cf7cf2b8836869ee
Reviewed-on: https://go-review.googlesource.com/c/go/+/542699
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Use a GODEBUG to choose which certificate policy field to use. If
x509usepolicies=1 is set, use the Policies field, otherwise use the
PolicyIdentifiers field.
Fixes#64248
Change-Id: I3f0b56102e0bac4ebe800497717c61c58ef3f092
Reviewed-on: https://go-review.googlesource.com/c/go/+/546916
Reviewed-by: Damien Neil <dneil@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Removes the RSA KEX based ciphers from the default list. This can be
reverted using the tlsrsakex GODEBUG.
Fixes#63413
Change-Id: Id221be3eb2f6c24b91039d380313f0c87d339f98
Reviewed-on: https://go-review.googlesource.com/c/go/+/541517
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Damien Neil <dneil@google.com>
Updates the default from 1.0 -> 1.2 for servers, bringing it in line
with clients. Add a GODEBUG setting, tls10server, which lets users
revert this change.
Fixes#62459
Change-Id: I2b82f85b1c2d527df1f9afefae4ab30a8f0ceb41
Reviewed-on: https://go-review.googlesource.com/c/go/+/541516
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Damien Neil <dneil@google.com>
This CL exports the previously unexported Alias type and
corresponding functions and methods per issue #63223.
Whether Alias types are used or not is controlled by
the gotypesalias setting with the GODEBUG environment
variable. Setting gotypesalias to "1" enables the Alias
types:
GODEBUG=gotypesalias=1
By default, gotypesalias is not set.
Adjust test cases that enable/disable the use of Alias
types to use -gotypesalias=1 or -gotypesalias=0 rather
than -alias and -alias=false for consistency and to
avoid confusion.
For #63223.
Change-Id: I51308cad3320981afac97dd8c6f6a416fdb0be55
Reviewed-on: https://go-review.googlesource.com/c/go/+/541737
Run-TryBot: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
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Reviewed-by: Robert Griesemer <gri@google.com>
Add the GODEBUG setting httpmuxgo121.
When set to "1", ServeMux behaves exactly like it did in Go 1.21.
Implemented by defining a new, unexported type, serveMux121, that
uses the original code.
Updates #61410.
Change-Id: I0a9d0fe2a2286e442d680393e62895ab50683cea
Reviewed-on: https://go-review.googlesource.com/c/go/+/530461
Run-TryBot: Jonathan Amsterdam <jba@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
This is a follow up of CL 526496.
Change-Id: I9f351951bf975e31befd36b9c951d195d2f8f9f7
GitHub-Last-Rev: 4307adafbf
GitHub-Pull-Request: golang/go#62590
Reviewed-on: https://go-review.googlesource.com/c/go/+/527576
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Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Auto-Submit: Keith Randall <khr@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
The Content-Length must be a valid numeric value, empty values should not be accepted.
See: https://www.rfc-editor.org/rfc/rfc9110.html#name-content-lengthFixes#61679
Change-Id: Icbcd933087fe5e50199b62ff34c58bf92a09d3d4
GitHub-Last-Rev: 932e46b55b
GitHub-Pull-Request: golang/go#61865
Reviewed-on: https://go-review.googlesource.com/c/go/+/517336
Reviewed-by: Damien Neil <dneil@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
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TryBot-Result: Gopher Robot <gobot@golang.org>
Add a new GODEBUG setting, tlsmaxrsasize, which allows controlling the
maximum RSA key size we will accept during TLS handshakes.
Change-Id: I52f060be132014d219f4cd438f59990011a35c96
Reviewed-on: https://go-review.googlesource.com/c/go/+/517495
Auto-Submit: Roland Shoemaker <roland@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Roland Shoemaker <roland@golang.org>
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When adding MPTCP support to address the proposal #56539, I missed the
GODEBUG setting from Russ Cox's plan:
I am inclined to say that we add MPTCP as an opt-in for a release or
two, and then make it opt-out. There should be a GODEBUG setting (...)
See: https://github.com/golang/go/issues/56539#issuecomment-1309294637
Thanks to andrius4669 for having reported this issue to me.
It makes sense to have this GODEBUG setting not to have to modify
applications to use MPTCP (if available). It can then be useful to
estimate the impact in case we want to switch from opt-in to opt-out
later.
The MPTCP E2E test has been modified to make sure we can enable MPTCP
either via the source code like it was already the case before or with
this environment variable:
GODEBUG=multipathtcp=1
The documentation has been adapted accordingly.
I don't know if it is too late for Go 1.21 but I had to put a version in
the documentation. The modification is small, the risk seems low and
this was supposed to be there from the beginning according to Russ Cox's
specifications. It can also be backported or only be present in the
future v1.22 if it is easier.
Note: I didn't re-open #56539 or open a new one. It is not clear to me
what I should do in this case.
Fixes#56539
Change-Id: I9201f4dc0b99e3643075a34c7032a95528c48fa0
Reviewed-on: https://go-review.googlesource.com/c/go/+/507375
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
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Reviewed-by: Damien Neil <dneil@google.com>
A //go:debug line mentioning an unknown or retired setting
should be diagnosed as making the program invalid. Do that.
We agreed on this in the proposal but I forgot to implement it.
Change-Id: Ie69072a1682d4eeb6866c02adbbb426f608567c4
Reviewed-on: https://go-review.googlesource.com/c/go/+/476280
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
