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601 Commits

Author SHA1 Message Date
Ian Lance Taylor
1ebfb082a7 runtime: remove unnecessary GOOS switch
Change-Id: I8f518e273c02110042b08f7c50c3d38a648c8b6e
Reviewed-on: https://go-review.googlesource.com/2281
Reviewed-by: Minux Ma <minux@golang.org>
2015-01-04 19:41:05 +00:00
Matthew Dempsky
537ddc9456 runtime: fix slicecopy return value for zero-width elements
Fixes #8620

Change-Id: Idb49e586919d21d07e94a39ed9ebb0562f403460
Reviewed-on: https://go-review.googlesource.com/2221
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-01-04 01:59:59 +00:00
Shenghou Ma
865e5e98b6 runtime: fix TestCgoExternalThreadSIGPROF again
Shell out to `uname -r` this time, so that the test will compile
even if the platform doesn't have syscall.Sysctl.

Change-Id: I3a19ab5d820bdb94586a97f4507b3837d7040525
Reviewed-on: https://go-review.googlesource.com/2271
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2015-01-03 05:49:22 +00:00
Shenghou Ma
2cbe27a272 runtime: skip TestCgoExternalThreadSIGPROF on OS X 10.6
The test program requires static constructor, which in turn needs
external linking to work, but external linking never works on 10.6.

This should fix the darwin-{386,amd64} builders.

Change-Id: I714fdd3e35f9a7e5f5659cf26367feec9412444f
Reviewed-on: https://go-review.googlesource.com/2235
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2015-01-03 03:18:46 +00:00
Josh Bleecher Snyder
17577e48c9 runtime: use SETEQ instead of JZ for cas
Change-Id: Ibabbca3988d39bdce584924173a912d45f50f0dd
Reviewed-on: https://go-review.googlesource.com/2243
Reviewed-by: Dave Cheney <dave@cheney.net>
Reviewed-by: Minux Ma <minux@golang.org>
2015-01-02 19:06:36 +00:00
David Crawshaw
8fa0cf1db2 runtime: remove unused export_test declarations
Change-Id: Iac28c4bbe949af5628cef8ecafdd59ab5d71e6cc
Reviewed-on: https://go-review.googlesource.com/2240
Reviewed-by: Keith Randall <khr@golang.org>
2015-01-01 18:44:36 +00:00
Shenghou Ma
1f28238557 runtime: provide a dummy value of _SIGPROF on plan9 and windows
Fixes build on plan9 and windows.

Change-Id: Ic9b02c641ab84e4f6d8149de71b9eb495e3343b2
Reviewed-on: https://go-review.googlesource.com/2233
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
2015-01-01 04:41:43 +00:00
Shenghou Ma
0b2a74e89c runtime/cgo: remove unused variable
I missed this one in golang.org/cl/2232 and only tested the patch
on openbsd/amd64.

Change-Id: I4ff437ae0bfc61c989896c01904b6d33f9bdf0ec
Reviewed-on: https://go-review.googlesource.com/2234
Reviewed-by: Minux Ma <minux@golang.org>
2015-01-01 03:14:56 +00:00
Shenghou Ma
77cd6197d7 runtime/cgo: initialize our pthread_create wrapper earlier on openbsd
This is a genuine bug exposed by our test for issue 9456: our wrapper
for pthread_create is not initialized until we initialize cgo itself,
but it is possible that a static constructor could call pthread_create,
and in that case, it will be calling a nil function pointer.

Fix that by also initializing the sys_pthread_create function pointer
inside our pthread_create wrapper function, and use a pthread_once to
make sure it is only initialized once.

Fix build for openbsd.

Change-Id: Ica4da2c21fcaec186fdd3379128ef46f0e767ed7
Reviewed-on: https://go-review.googlesource.com/2232
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2015-01-01 02:52:34 +00:00
Shenghou Ma
5da9c8cd0a runtime: ignore SIGPROF to foreign threads before cgocallback is fully initialized
Some libraries, for example, OpenBLAS, create work threads in a global constructor.
If we're doing cpu profiling, it's possible that SIGPROF might come to some of the
worker threads before we make our first cgo call. Cgocallback used to terminate the
process when that happens, but it's better to miss a couple profiling signals than
to abort in this case.

Fixes #9456.

Change-Id: I112b8e1a6e10e6cc8ac695a4b518c0f577309b6b
Reviewed-on: https://go-review.googlesource.com/2141
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2014-12-31 23:10:44 +00:00
Anthony Martin
3d032d7653 runtime: consolidate arch-specific signal handlers on Plan 9
Change-Id: I4379418853c523fc9aaeb5d6f37bc96117841418
Reviewed-on: https://go-review.googlesource.com/1786
Reviewed-by: David du Colombier <0intro@gmail.com>
Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>
2014-12-30 14:36:15 +00:00
David du Colombier
29b4e34cf2 runtime: rename atoi to _atoi on Plan 9
Following change 2154, the goatoi function
was renamed atoi.

However, this definition conflicts with the
atoi function defined in the Plan 9 runtime,
which takes a []byte instead of a string.

This change fixes the build on Plan 9.

Change-Id: Ia0f7ca2f965bd5e3cce3177bba9c806f64db05eb
Reviewed-on: https://go-review.googlesource.com/2165
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2014-12-29 17:04:24 +00:00
Keith Randall
0bb8fc6614 runtime: remove go prefix from a few routines
They are no longer needed now that C is gone.

goatoi -> atoi
gofuncname/funcname -> funcname/cfuncname
goroundupsize -> already existing roundupsize

Change-Id: I278bc33d279e1fdc5e8a2a04e961c4c1573b28c7
Reviewed-on: https://go-review.googlesource.com/2154
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
2014-12-29 15:18:29 +00:00
Shenghou Ma
ab0535ae3f liblink, cmd/ld, runtime: remove stackguard1
Now that we've removed all the C code in runtime and the C compilers,
there is no need to have a separate stackguard field to check for C
code on Go stack.

Remove field g.stackguard1 and rename g.stackguard0 to g.stackguard.
Adjust liblink and cmd/ld as necessary.

Change-Id: I54e75db5a93d783e86af5ff1a6cd497d669d8d33
Reviewed-on: https://go-review.googlesource.com/2144
Reviewed-by: Keith Randall <khr@golang.org>
2014-12-29 07:36:07 +00:00
Keith Randall
b1f29b2d44 runtime: get rid of goalg, no longer needed
The goalg function was a holdover from when we had algorithm
tables in both C and Go.  It is no longer needed.

Change-Id: Ia0c1af35bef3497a899f22084a1a7b42daae72a0
Reviewed-on: https://go-review.googlesource.com/2099
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2014-12-28 18:42:39 +00:00
Keith Randall
b2a950bb73 runtime: rename gothrow to throw
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>
2014-12-28 06:16:16 +00:00
mattn
e26e3fa25a reflect, runtime: gofmt
Change-Id: I5437b3a36181373d8ff33225d7520ab321459de9
Reviewed-on: https://go-review.googlesource.com/2084
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2014-12-26 04:43:33 +00:00
Dmitry Vyukov
ce9a4afa6f runtime: simplify procresize
Currently we do very a complex rebalancing of runnable goroutines
between queues, which tries to preserve scheduling fairness.
Besides being complex and error-prone, it also destroys all locality
of scheduling.

This change uses simpler scheme: leave runnable goroutines where
they are, during starttheworld start all Ps with local work,
plus start one additional P in case we have excessive runnable
goroutines in local queues or in the global queue.

The schedler must be able to operate efficiently w/o the rebalancing,
because garbage collections do not have to happen frequently.

The immediate need is execution tracing support: handling of
garabage collection which does stoptheworld/starttheworld several
times becomes exceedingly complex if the current execution can
jump between Ps during starttheworld.

Change-Id: I4fdb7a6d80ca4bd08900d0c6a0a252a95b1a2c90
Reviewed-on: https://go-review.googlesource.com/1951
Reviewed-by: Rick Hudson <rlh@golang.org>
2014-12-25 10:52:55 +00:00
David du Colombier
10be797578 runtime: fix exit on Plan 9
Add a nil byte at the end of the itoa buffer,
before calling gostringnocopy. This prevents
gostringnocopy to read past the buffer size.

Change-Id: I87494a8dd6ea45263882536bf6c0f294eda6866d
Reviewed-on: https://go-review.googlesource.com/2033
Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>
2014-12-23 18:54:39 +00:00
Alex Brainman
20dce04742 runtime: remove thunk_windows.s
Change-Id: I171298e7942093e9cc82e3a0c4fcbb5b10298816
Reviewed-on: https://go-review.googlesource.com/1998
Reviewed-by: Minux Ma <minux@golang.org>
2014-12-23 05:12:52 +00:00
Shenghou Ma
1050c4197a runtime: add comments for blank import of "unsafe"
Change-Id: Iaad548ea90d3b70341a723450d5e4d4c2b88856f
Reviewed-on: https://go-review.googlesource.com/2063
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2014-12-23 05:09:07 +00:00
Shenghou Ma
e98f2179b1 runtime: fix build for arm and ppc64/ppc64le
Change-Id: I17ddcb541dfac8b1e48e01ee005563031b6ade2a
Reviewed-on: https://go-review.googlesource.com/2062
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2014-12-23 04:48:14 +00:00
Alex Brainman
7f4c26850a runtime: import unsafe in os_windows.go (fixes windows build)
Change-Id: I55419cb580e6d18cf1c17c3e7bb8777ed6d794e7
Reviewed-on: https://go-review.googlesource.com/1995
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2014-12-23 04:14:53 +00:00
Russ Cox
7a524a1036 runtime: remove thunk.s
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>
2014-12-23 03:17:22 +00:00
Ian Lance Taylor
8a853aa5cb runtime: correct ptrSize test in Linux version of sysReserve
Change-Id: I90a8ca51269528a307e0d6f52436fc7913cd7900
Reviewed-on: https://go-review.googlesource.com/1541
Reviewed-by: Russ Cox <rsc@golang.org>
2014-12-23 02:18:29 +00:00
Austin Clements
675eb72c28 runtime: run libc SIGSETXID and SIGCANCEL handlers on signal stack
These signals are used by glibc to broadcast setuid/setgid to all
threads and to send pthread cancellations.  Unlike other signals, the
Go runtime does not intercept these because they must invoke the libc
handlers (see issues #3871 and #6997).  However, because 1) these
signals may be issued asynchronously by a thread running C code to
another thread running Go code and 2) glibc does not set SA_ONSTACK
for its handlers, glibc's signal handler may be run on a Go stack.
Signal frames range from 1.5K on amd64 to many kilobytes on ppc64, so
this may overflow the Go stack and corrupt heap (or other stack) data.

Fix this by ensuring that these signal handlers have the SA_ONSTACK
flag (but not otherwise taking over the handler).

This has been a problem since Go 1.1, but it's likely that people
haven't encountered it because it only affects setuid/setgid and
pthread_cancel.

Fixes #9600.

Change-Id: I6cf5f5c2d3aa48998d632f61f1ddc2778dcfd300
Reviewed-on: https://go-review.googlesource.com/1887
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2014-12-23 01:33:36 +00:00
Keith Randall
53c5226f9f runtime: make stack frames fixed size by modifying goproc/deferproc.
Calls to goproc/deferproc used to push & pop two extra arguments,
the argument size and the function to call.  Now, we allocate space
for those arguments in the outargs section so we don't have to
modify the SP.

Defers now use the stack pointer (instead of the argument pointer)
to identify which frame they are associated with.

A followon CL might simplify funcspdelta and some of the stack
walking code.

Fixes issue #8641

Change-Id: I835ec2f42f0392c5dec7cb0fe6bba6f2aed1dad8
Reviewed-on: https://go-review.googlesource.com/1601
Reviewed-by: Russ Cox <rsc@golang.org>
2014-12-23 01:08:29 +00:00
Keith Randall
c6669e7af5 runtime: fix nacl build, hashmap overflow field offset was incorrect.
Change-Id: Ieb305b2a4d4ef28d70a8b8ece703f495c5af0529
Reviewed-on: https://go-review.googlesource.com/2051
Reviewed-by: Keith Randall <khr@golang.org>
2014-12-22 23:25:24 +00:00
Keith Randall
cda0ea1c0e runtime: a better fallback hash
For arm and powerpc, as well as x86 without aes instructions.
Contains a mixture of ideas from cityhash and xxhash.

Compared to our old fallback on ARM, it's ~no slower on
small objects and up to ~50% faster on large objects.  More
importantly, it is a much better hash function and thus has
less chance of bad behavior.

Fixes #8737

benchmark                         old ns/op     new ns/op     delta
BenchmarkHash5                    173           181           +4.62%
BenchmarkHash16                   252           212           -15.87%
BenchmarkHash64                   575           419           -27.13%
BenchmarkHash1024                 7173          3995          -44.31%
BenchmarkHash65536                516940        313173        -39.42%
BenchmarkHashStringSpeed          300           279           -7.00%
BenchmarkHashBytesSpeed           478           424           -11.30%
BenchmarkHashInt32Speed           217           207           -4.61%
BenchmarkHashInt64Speed           262           231           -11.83%
BenchmarkHashStringArraySpeed     609           631           +3.61%

Change-Id: I0a9335028f32b10ad484966e3019987973afd3eb
Reviewed-on: https://go-review.googlesource.com/1360
Reviewed-by: Russ Cox <rsc@golang.org>
2014-12-22 22:41:01 +00:00
Keith Randall
fbc56cf050 runtime: hashmap: move overflow pointer to end of bucket
Pointers to zero-sized values may end up pointing to the next
object in memory, and possibly off the end of a span.  This
can cause memory leaks and/or confuse the garbage collector.

By putting the overflow pointer at the end of the bucket, we
make sure that pointers to any zero-sized keys or values don't
accidentally point to the next object in memory.

fixes #9384

Change-Id: I5d434df176984cb0210b4d0195dd106d6eb28f73
Reviewed-on: https://go-review.googlesource.com/1869
Reviewed-by: Russ Cox <rsc@golang.org>
2014-12-22 22:25:48 +00:00
Alex Brainman
79a4a779a7 syscall: clean up TestStdcallAndCDeclCallbacks to have no warnings
Fixes #9188

Change-Id: Ifbf5d9fa78a4f4ceb7f92d42494fe37fa7878c45
Reviewed-on: https://go-review.googlesource.com/1930
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2014-12-22 00:31:57 +00:00
mischief
640c0f3849 runtime: fix brk_ signature for plan9
with uintptr, the check for < 0 will never succeed in mem_plan9.go's
sbrk() because the brk_ syscall returns -1 on failure. fixes the plan9/amd64 build.

this failed on plan9/amd64 because of the attempt to allocate 136GB in mallocinit(),
which failed. it was just by chance that on plan9/386 allocations never failed.

Change-Id: Ia3059cf5eb752e20d9e60c9619e591b80e8fb03c
Reviewed-on: https://go-review.googlesource.com/1590
Reviewed-by: Anthony Martin <ality@pbrane.org>
Reviewed-by: David du Colombier <0intro@gmail.com>
Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>
2014-12-20 21:41:44 +00:00
Matthew Dempsky
481ce36ec4 runtime: simplify cpuprof hash calculation
"x*41" computes the same value as "x*31 + x*7 + x*3" and (when
compiled by gc) requires just one multiply instruction instead of
three.

Alternatively, the expression could be written as "(x<<2+x)<<3 + x" to
use shifts instead of multiplies (which is how GCC optimizes "x*41").
But gc currently emits suboptimal instructions for this expression
anyway (e.g., separate SHL+ADD instructions rather than LEA on
386/amd64). Also, if such an optimization was worthwhile, it would
seem better to implement it as part of gc's strength reduction logic.

Change-Id: I7156b793229d723bbc9a52aa9ed6111291335277
Reviewed-on: https://go-review.googlesource.com/1830
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2014-12-19 02:50:40 +00:00
Alex Brainman
3f19541752 runtime: use go generate for zcallback_windows.go
replacement for CL 180640043

Change-Id: I8ff36645cfcbbda338faf7b29cbfdb95c47d5ec4
Reviewed-on: https://go-review.googlesource.com/1765
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2014-12-19 02:45:40 +00:00
Shenghou Ma
340ef004d6 runtime/cgo: guard against redefinition of PTHREAD_KEYS_MAX
Fixes #9374.

Change-Id: Ic53757eba98fc43bcd24e25e03876fef917b4da1
Reviewed-on: https://go-review.googlesource.com/1751
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2014-12-18 21:23:25 +00:00
Guobiao Mei
6ce3cd18fa runtime: fix a minor typo in comments
Change-Id: I13a8aacd1b8243c992b539ab6bf7b5dff2a1393a
Reviewed-on: https://go-review.googlesource.com/1757
Reviewed-by: Minux Ma <minux@golang.org>
2014-12-18 20:35:56 +00:00
Rick Hudson
1b0b0db6fb runtime: add profiling infrastructure for the Concurrent GC
Change-Id: Ia7a007444eeb1503cec27367a5c6699ce0bf4af6
Reviewed-on: https://go-review.googlesource.com/1441
Reviewed-by: Austin Clements <austin@google.com>
2014-12-16 22:15:51 +00:00
Keith Randall
50bc3d5bbc runtime: fix deadlock in runtime.Stack
It shouldn't semacquire() inside an acquirem(), the runtime
thinks that means deadlock.  It actually isn't a deadlock, but it
looks like it because acquirem() does m.locks++.

Candidate for inclusion in 1.4.1.  runtime.Stack with all=true
is pretty unuseable in GOMAXPROCS>1 environment.

fixes #9321

Change-Id: Iac6b664217d24763b9878c20e49229a1ecffc805
Reviewed-on: https://go-review.googlesource.com/1600
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
2014-12-16 17:04:45 +00:00
Brad Fitzpatrick
fccd942803 runtime: gofmt
Fixes #9339

Change-Id: I22faf2593cb73f42612c2c2bfe38de001fb2746b
Reviewed-on: https://go-review.googlesource.com/1630
Reviewed-by: Andrew Gerrand <adg@golang.org>
2014-12-16 06:16:00 +00:00
Keith Randall
df1739c77d runtime: if key type is reflexive, don't call equal(k, k)
Most types are reflexive (k == k for all k of type t), so don't
bother calling equal(k, k) when the key type is reflexive.

Change-Id: Ia716b4198b8b298687843b94b878dbc5e8fc2c65
Reviewed-on: https://go-review.googlesource.com/1480
Reviewed-by: Russ Cox <rsc@golang.org>
2014-12-15 21:43:49 +00:00
David Crawshaw
324f38a222 runtime: shrink initial arena if reservation fails
Fixes #9311

Change-Id: I2f142e65a54c0391084316d79a42714ba42dd8b9
Reviewed-on: https://go-review.googlesource.com/1514
Reviewed-by: Keith Randall <khr@golang.org>
2014-12-15 20:55:33 +00:00
Russ Cox
557a61d270 cmd/gc: add //go:nowritebarrier to diagnose unintended write barriers
//go:nowritebarrier can only be used in package runtime.
It does not disable write barriers; it is an assertion, checked
by the compiler, that the following function needs no write
barriers.

Change-Id: Id7978b779b66dc1feea39ee6bda9fd4d80280b7c
Reviewed-on: https://go-review.googlesource.com/1224
Reviewed-by: Rick Hudson <rlh@golang.org>
2014-12-12 20:48:10 +00:00
Keith Randall
1757b5cc74 runtime: fix nacl build
Change-Id: Ifa8b2d1d1cebe72f795db34974584a888d55cbd8
Reviewed-on: https://go-review.googlesource.com/1362
Reviewed-by: Keith Randall <khr@golang.org>
2014-12-11 07:31:32 +00:00
Keith Randall
7a4a64e8f3 runtime: faster aeshash implementation
The aesenc instruction has high latency.  For hashing large objects,
hash several streams in parallel.

benchmark                         old ns/op     new ns/op     delta
BenchmarkHash5                    7.02          7.45          +6.13%
BenchmarkHash16                   6.53          6.94          +6.28%
BenchmarkHash32                   8.38          8.26          -1.43%
BenchmarkHash64                   12.6          12.0          -4.76%
BenchmarkHash1024                 247           62.9          -74.53%
BenchmarkHash65536                17335         2966          -82.89%
BenchmarkHashInt32Speed           14.7          14.9          +1.36%
BenchmarkHashInt64Speed           14.6          14.9          +2.05%
BenchmarkHashBytesSpeed           35.4          28.6          -19.21%
BenchmarkHashStringSpeed          22.0          20.4          -7.27%
BenchmarkHashStringArraySpeed     65.8          56.3          -14.44%

Change-Id: Ia8ba03063acc64a9066b8ab2d79f2c9aaac1770f
Reviewed-on: https://go-review.googlesource.com/1330
Reviewed-by: Russ Cox <rsc@golang.org>
2014-12-11 05:23:00 +00:00
David Crawshaw
bee8ae1185 runtime: send android stderr to /dev/log/main
I tried to submit this in Go 1.4 as cl/107540044 but tripped over the
changes for getting C off the G stack. This is a rewritten version that
avoids cgo and works directly with the underlying log device.

Change-Id: I14c227dbb4202690c2c67c5a613d6c6689a6662a
Reviewed-on: https://go-review.googlesource.com/1285
Reviewed-by: Keith Randall <khr@golang.org>
2014-12-10 22:06:13 +00:00
Keith Randall
6820be25da runtime: clean up & go-ify the hash function seeder
Change-Id: I0e95f8a5962c547da20e19a356ae1cf8375c9107
Reviewed-on: https://go-review.googlesource.com/1270
Reviewed-by: Russ Cox <rsc@golang.org>
2014-12-10 21:15:35 +00:00
Keith Randall
b796cbc406 runtime: fix finalizer iterator
It could only handle one finalizer before it raised an out-of-bounds error.

Fixes issue #9172

Change-Id: Ibb4d0c8aff2d78a1396e248c7129a631176ab427
Reviewed-on: https://go-review.googlesource.com/1201
Reviewed-by: Russ Cox <rsc@golang.org>
2014-12-10 16:33:26 +00:00
Rick Hudson
2937d88af5 runtime: fix some comment formatting
Change-Id: Ife7d6ce1131ff26444f09e8fda4f61344e669e21
Reviewed-on: https://go-review.googlesource.com/1260
Reviewed-by: Russ Cox <rsc@golang.org>
2014-12-09 22:08:45 +00:00
Austin Clements
76f71959c8 runtime: restore error message on early needm
needm used to print an error before exiting when it was called too
early, but this error was lost in the transition to Go.  Bring back
the error so we don't silently exit(1) when this happens.

Change-Id: I8086932783fd29a337d7dea31b9d6facb64cb5c1
Reviewed-on: https://go-review.googlesource.com/1226
Reviewed-by: Russ Cox <rsc@golang.org>
2014-12-09 20:12:14 +00:00
Keith Randall
8eb8b40a49 runtime: use doubly-linked lists for channel send/recv queues.
Avoids a potential O(n^2) performance problem when dequeueing
from very popular channels.

benchmark                old ns/op     new ns/op     delta
BenchmarkChanPopular     2563782       627201        -75.54%

Change-Id: I231aaeafea0ecd93d27b268a0b2128530df3ddd6
Reviewed-on: https://go-review.googlesource.com/1200
Reviewed-by: Russ Cox <rsc@golang.org>
2014-12-08 19:20:12 +00:00