Change Cond implementation to use a notification list such that waiters
can first register for a notification, release the lock, then actually
wait. Signalers never have to park anymore.
This is intended to address an issue in the previous implementation
where Broadcast could fail to signal all waiters.
Results of the existing benchmark are below.
Original New Diff
BenchmarkCond1-48 2000000 745 ns/op 755 +1.3%
BenchmarkCond2-48 1000000 1545 ns/op 1532 -0.8%
BenchmarkCond4-48 300000 3833 ns/op 3896 +1.6%
BenchmarkCond8-48 200000 10049 ns/op 10257 +2.1%
BenchmarkCond16-48 100000 21123 ns/op 21236 +0.5%
BenchmarkCond32-48 30000 40393 ns/op 41097 +1.7%
Fixes#14064
Change-Id: I083466d61593a791a034df61f5305adfb8f1c7f9
Reviewed-on: https://go-review.googlesource.com/18892
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Caleb Spare <cespare@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
runtime/internal/sys will hold system-, architecture- and config-
specific constants.
Updates #11647
Change-Id: I6db29c312556087a42e8d2bdd9af40d157c56b54
Reviewed-on: https://go-review.googlesource.com/16817
Reviewed-by: Russ Cox <rsc@golang.org>
This change breaks out most of the atomics functions in the runtime
into package runtime/internal/atomic. It adds some basic support
in the toolchain for runtime packages, and also modifies linux/arm
atomics to remove the dependency on the runtime's mutex. The mutexes
have been replaced with spinlocks.
all trybots are happy!
In addition to the trybots, I've tested on the darwin/arm64 builder,
on the darwin/arm builder, and on a ppc64le machine.
Change-Id: I6698c8e3cf3834f55ce5824059f44d00dc8e3c2f
Reviewed-on: https://go-review.googlesource.com/14204
Run-TryBot: Michael Matloob <matloob@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Stip uninteresting bottom and top frames from trace stacks.
This makes both binary and json trace files smaller,
and also makes stacks shorter and more readable in the viewer.
Change-Id: Ib9c80ccc280504f0e235f867f53f1d2652c41583
Reviewed-on: https://go-review.googlesource.com/5523
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
Rename "gothrow" to "throw" now that the C version of "throw"
is no longer needed.
This change is purely mechanical except in panic.go where the
old version of "throw" has been deleted.
sed -i "" 's/[[:<:]]gothrow[[:>:]]/throw/g' runtime/*.go
Change-Id: Icf0752299c35958b92870a97111c67bcd9159dc3
Reviewed-on: https://go-review.googlesource.com/2150
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>
Replace with uses of //go:linkname in Go files, direct use of name in .s files.
The only one that really truly needs a jump is reflect.call; the jump is now
next to the runtime.reflectcall assembly implementations.
Change-Id: Ie7ff3020a8f60a8e4c8645fe236e7883a3f23f46
Reviewed-on: https://go-review.googlesource.com/1962
Reviewed-by: Austin Clements <austin@google.com>
The SudoG used to sit on the stack, so it was cheap to allocated
and didn't need to be cleaned up when finished.
For the conversion to Go, we had to move sudog off the stack
for a few reasons, so we added a cache of recently used sudogs
to keep allocation cheap. But we didn't add any of the necessary
cleanup before adding a SudoG to the new cache, and so the cached
SudoGs had stale pointers inside them that have caused all sorts
of awful, hard to debug problems.
CL 155760043 made sure SudoG.elem is cleaned up.
CL 150520043 made sure SudoG.selectdone is cleaned up.
This CL makes sure SudoG.next, SudoG.prev, and SudoG.waitlink
are cleaned up. I should have done this when I did the other two
fields; instead I wasted a week tracking down a leak they caused.
A dangling SudoG.waitlink can point into a sudogcache list that
has been "forgotten" in order to let the GC collect it, but that
dangling .waitlink keeps the list from being collected.
And then the list holding the SudoG with the dangling waitlink
can find itself in the same situation, and so on. We end up
with lists of lists of unusable SudoGs that are still linked into
the object graph and never collected (given the right mix of
non-trivial selects and non-channel synchronization).
More details in golang.org/issue/9110.
Fixes#9110.
LGTM=r
R=r
CC=dvyukov, golang-codereviews, iant, khr
https://golang.org/cl/177870043
Manifested as increased memory usage in a Google production system.
Not an unbounded leak, but can significantly increase the number
of sudogs allocated between garbage collections.
I checked all the other calls to acquireSudog.
This is the only one that was missing a releaseSudog.
LGTM=r, dneil
R=dneil, r
CC=golang-codereviews
https://golang.org/cl/169260043
This change was necessary on the dev.garbage branch
to keep the garbage collector from seeing pointers into
invalid heap areas.
On this default (Go 1.4) branch, the change removes
some possibility for memory leaks.
LGTM=khr
R=golang-codereviews, khr
CC=golang-codereviews, iant, r, rlh
https://golang.org/cl/155760043
semacquire might need to park the currently running G. It can
only park if called from the G stack (because it has no way of
saving the M stack state). So all calls to semacquire must come
from the G stack.
The three violators are GOMAXPROCS, ReadMemStats, and WriteHeapDump.
This change moves the semacquire call earlier, out of their C code
and into their Go code.
This seldom caused bugs because semacquire seldom actually had
to park the caller. But it did happen intermittently.
Fixes#8749
LGTM=dvyukov
R=golang-codereviews, dvyukov, bradfitz
CC=golang-codereviews
https://golang.org/cl/144940043
The C header files are the single point of truth:
every C enum constant Foo is available to Go as _Foo.
Remove or redirect duplicate Go declarations so they
cannot be out of sync.
Eventually we will need to put constants in Go, but for now having
them be out of sync with C is too risky. These predate the build
support for auto-generating Go constants from the C definitions.
LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/141510043
