Fixes#1641.
Actually it side steps the real issue, which is that the
setitimer(2) implementation on OS X is not useful for
profiling of multi-threaded programs. I filed the below
using the Apple Bug Reporter.
/*
Filed as Apple Bug Report #9177434.
This program creates a new pthread that loops, wasting cpu time.
In the main pthread, it sleeps on a condition that will never come true.
Before doing so it sets up an interval timer using ITIMER_PROF.
The handler prints a message saying which thread it is running on.
POSIX does not specify which thread should receive the signal, but
in order to be useful in a user-mode self-profiler like pprof or gprof
http://code.google.com/p/google-perftoolshttp://www.delorie.com/gnu/docs/binutils/gprof_25.html
it is important that the thread that receives the signal is the one
whose execution caused the timer to expire.
Linux and FreeBSD handle this by sending the signal to the process's
queue but delivering it to the current thread if possible:
http://lxr.linux.no/linux+v2.6.38/kernel/signal.c#L802
807 /*
808 * Now find a thread we can wake up to take the signal off the queue.
809 *
810 * If the main thread wants the signal, it gets first crack.
811 * Probably the least surprising to the average bear.
812 * /
http://fxr.watson.org/fxr/source/kern/kern_sig.c?v=FREEBSD8;im=bigexcerpts#L1907
1914 /*
1915 * Check if current thread can handle the signal without
1916 * switching context to another thread.
1917 * /
On those operating systems, this program prints:
$ ./a.out
signal on cpu-chewing looper thread
signal on cpu-chewing looper thread
signal on cpu-chewing looper thread
signal on cpu-chewing looper thread
signal on cpu-chewing looper thread
signal on cpu-chewing looper thread
signal on cpu-chewing looper thread
signal on cpu-chewing looper thread
signal on cpu-chewing looper thread
signal on cpu-chewing looper thread
$
The OS X kernel does not have any such preference. Its get_signalthread
does not prefer current_thread(), in contrast to the other two systems,
so the signal gets delivered to the first thread in the list that is able to
handle it, which ends up being the main thread in this experiment.
http://fxr.watson.org/fxr/source/bsd/kern/kern_sig.c?v=xnu-1456.1.26;im=excerpts#L1666
$ ./a.out
signal on sleeping main thread
signal on sleeping main thread
signal on sleeping main thread
signal on sleeping main thread
signal on sleeping main thread
signal on sleeping main thread
signal on sleeping main thread
signal on sleeping main thread
signal on sleeping main thread
signal on sleeping main thread
$
The fix is to make get_signalthread use the same heuristic as
Linux and FreeBSD, namely to use current_thread() if possible
before scanning the process thread list.
*/
#include <sys/time.h>
#include <sys/signal.h>
#include <pthread.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
static void handler(int);
static void* looper(void*);
static pthread_t pmain, ploop;
int
main(void)
{
struct itimerval it;
struct sigaction sa;
pthread_cond_t cond;
pthread_mutex_t mu;
memset(&sa, 0, sizeof sa);
sa.sa_handler = handler;
sa.sa_flags = SA_RESTART;
memset(&sa.sa_mask, 0xff, sizeof sa.sa_mask);
sigaction(SIGPROF, &sa, 0);
pmain = pthread_self();
pthread_create(&ploop, 0, looper, 0);
memset(&it, 0, sizeof it);
it.it_interval.tv_usec = 10000;
it.it_value = it.it_interval;
setitimer(ITIMER_PROF, &it, 0);
pthread_mutex_init(&mu, 0);
pthread_mutex_lock(&mu);
pthread_cond_init(&cond, 0);
for(;;)
pthread_cond_wait(&cond, &mu);
return 0;
}
static void
handler(int sig)
{
static int nsig;
pthread_t p;
p = pthread_self();
if(p == pmain)
printf("signal on sleeping main thread\n");
else if(p == ploop)
printf("signal on cpu-chewing looper thread\n");
else
printf("signal on %p\n", (void*)p);
if(++nsig >= 10)
exit(0);
}
static void*
looper(void *v)
{
for(;;);
}
R=r
CC=golang-dev
https://golang.org/cl/4273113
label.go:30:1: error: label ‘L6’ already defined
label.go:28:1: note: previous definition of ‘L6’ was here
label.go:23:1: error: label ‘L4’ defined and not used
label.go:52:2: error: label ‘defalt’ defined and not used
label.go:17:1: error: label ‘L2’ defined and not used
label.go:26:1: error: label ‘L5’ defined and not used
label.go:20:1: error: label ‘L3’ defined and not used
label.go:14:1: error: label ‘L1’ defined and not used
label1.go:32:13: error: invalid continue label ‘L2’
label1.go:44:13: error: invalid continue label ‘L3’
label1.go:52:10: error: invalid break label ‘L4’
label1.go:55:13: error: invalid continue label ‘L4’
label1.go:65:9: error: invalid break label ‘L5’
label1.go:68:12: error: invalid continue label ‘L5’
label1.go:76:10: error: invalid break label ‘L1’
label1.go:79:13: error: invalid continue label ‘L1’
R=rsc
CC=golang-dev
https://golang.org/cl/4275078
Also fix comment.
The only caller of chanrecv initializes the value to false, so
this patch makes no difference at present. But it seems like
the right thing to do.
R=rsc
CC=golang-dev
https://golang.org/cl/4312053
Correctly distinguish between lhs and rhs identifiers
and resolve/declare them accordingly.
Collect field and method names in respective scopes
(will be available after some minor AST API changes).
Also collect imports since it's useful to have that
list directly w/o having to re-traverse the AST
(will also be available after some minor AST API changes).
No external API changes in this CL.
R=rsc, rog
CC=golang-dev
https://golang.org/cl/4271061
Change M-x gofmt to display errors in a new buffer instead of
clobbering the current buffer.
Add gofmt-before-save, which runs gofmt when in go-mode. This
can be used with before-save-hook. Add to your .emacs:
(add-hook 'before-save-hook 'gofmt-before-save)
R=rsc, aclements, amdragon
CC=golang-dev
https://golang.org/cl/4276059
The top level bytes.Buffer is always there and can be re-used.
Rpc goes from 83 to 79 mallocs per round trip.
R=rsc
CC=golang-dev
https://golang.org/cl/4271062
- StartProcess will work with relative (to attr.Dir, not
current directory) executable filenames
- StartProcess will only work if executable filename points
to the real file, it will not search for executable in the
$PATH list and others (see CreateProcess manual for details)
- StartProcess argv strings can contain any characters
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/4306041
This patch adds a connection cache and keep-alive
support to Transport, which is used by the
HTTP client.
It's also structured such that it's easy to add
HTTP pipelining in the future.
R=rsc, petar-m, bradfitzwork, r
CC=golang-dev
https://golang.org/cl/4272045
Revert changes to printer.Config. Pass in the
nodeSizes map trough an internal helper function.
R=golang-dev, rsc1
CC=golang-dev
https://golang.org/cl/4309042
Use memoization to avoid repeated recomputation of nested
node sizes. Speeds up testdata/slow.input by several orders
of magnitude.
- added respective test case
- added timeout to test code
- deleted some unrelated unused code
Fixes#1628.
R=rsc, r
CC=golang-dev
https://golang.org/cl/4274075
This change had already been made in revision 7371, but
was then undone with changes in revision 7606.
R=golang-dev, rsc1
CC=golang-dev
https://golang.org/cl/4239064
