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  1. 25 Mar, 2011 8 commits
    • Russ Cox's avatar
      runtime/pprof: disable test on darwin · 071d212a
      Russ Cox authored 
      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-perftools
   http://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
      071d212a
    • Ian Lance Taylor's avatar
      test: match gccgo error messages for label.go and label1.go. · 8beb4be8
      Ian Lance Taylor authored 
      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
      8beb4be8
    • Ian Lance Taylor's avatar
      runtime: always set *received in chanrecv. · 7c616b38
      Ian Lance Taylor authored 
      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
      7c616b38
    • Ian Lance Taylor's avatar
      runtime/darwin: remove unused local variables. · f6d0e811
      Ian Lance Taylor authored 
      R=rsc
CC=golang-dev
https://golang.org/cl/4309049
      f6d0e811
    • Russ Cox's avatar
      http/pprof: cpu profiling support · e857dd5d
      Russ Cox authored 
      R=r
CC=golang-dev
https://golang.org/cl/4280060
      e857dd5d
    • Roger Pau Monné's avatar
      http: modified perl cgi test to remove newline from env variables · 500effe7
      Roger Pau Monné authored 
      Fixes #1639

R=golang-dev, bradfitzgo
CC=golang-dev
https://golang.org/cl/4291069
      500effe7
    • Russ Cox's avatar
      runtime: fix arm build · 1f223463
      Russ Cox authored 
      R=adg, dfc, r
CC=golang-dev
https://golang.org/cl/4296042
      1f223463
    • Russ Cox's avatar
      A+C: Roger Pau Monné (individual CLA) · c0168f8f
      Russ Cox authored 
      R=golang-dev
CC=golang-dev
https://golang.org/cl/4276077
      c0168f8f
  3. 24 Mar, 2011 7 commits
  5. 23 Mar, 2011 18 commits
  7. 22 Mar, 2011 7 commits