Work around profiling kernel bug with signal masks.
Still broken on 64-bit Snow Leopard kernel,
but I think we can ignore that one and let people
upgrade to Lion.
Add new trivial tools addr2line and objdump to take
the place of the GNU tools of the same name, since
those are not installed on OS X.
Adapt pprof to invoke 'go tool addr2line' and
'go tool objdump' if the system tools do not exist.
Clean up disassembly of base register on amd64.
Fixes#2008.
R=golang-dev, bradfitz, mikioh.mikioh, r, iant
CC=golang-dev
https://golang.org/cl/5697066
Makes it possible for client code to maintain its own profiles,
and also reduces the API surface by giving us a type that
models built-in profiles.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5684056
Same idea as heap profile: how did each thread get created?
Low memory (256 bytes per OS thread), high reward for
programs that suddenly have many threads running.
Fixes#1477.
R=golang-dev, r, dvyukov
CC=golang-dev
https://golang.org/cl/5639059
Unexports runtime.MemStats and rename MemStatsType to MemStats.
The new accessor requires passing a pointer to a user-allocated
MemStats structure.
Fixes#2572.
R=bradfitz, rsc, bradfitz, gustavo
CC=golang-dev, remy
https://golang.org/cl/5616072
Consequently, remove many package Makefiles,
and shorten the few that remain.
gomake becomes 'go tool make'.
Turn off test phases of run.bash that do not work,
flagged with $BROKEN. Future CLs will restore these,
but this seemed like a big enough CL already.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5601057
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
The old heap maps used a multilevel table, but that
was overkill: there are only 1M entries on a 32-bit
machine and we can arrange to use a dense address
range on a 64-bit machine.
The heap map is in bss. The assumption is that if
we don't touch the pages they won't be mapped in.
Also moved some duplicated memory allocation
code out of the OS-specific files.
R=r
CC=golang-dev
https://golang.org/cl/4118042
