473 lines
14 KiB
C
473 lines
14 KiB
C
#include "private/pthread_support.h"
|
|
|
|
#if defined(GC_PTHREADS) && !defined(GC_SOLARIS_THREADS) \
|
|
&& !defined(GC_IRIX_THREADS) && !defined(GC_WIN32_THREADS) \
|
|
&& !defined(GC_DARWIN_THREADS) && !defined(GC_AIX_THREADS)
|
|
|
|
#include <signal.h>
|
|
#include <semaphore.h>
|
|
#include <errno.h>
|
|
#include <unistd.h>
|
|
|
|
#if DEBUG_THREADS
|
|
|
|
#ifndef NSIG
|
|
# if defined(MAXSIG)
|
|
# define NSIG (MAXSIG+1)
|
|
# elif defined(_NSIG)
|
|
# define NSIG _NSIG
|
|
# elif defined(__SIGRTMAX)
|
|
# define NSIG (__SIGRTMAX+1)
|
|
# else
|
|
--> please fix it
|
|
# endif
|
|
#endif
|
|
|
|
void GC_print_sig_mask()
|
|
{
|
|
sigset_t blocked;
|
|
int i;
|
|
|
|
if (pthread_sigmask(SIG_BLOCK, NULL, &blocked) != 0)
|
|
ABORT("pthread_sigmask");
|
|
GC_printf0("Blocked: ");
|
|
for (i = 1; i < NSIG; i++) {
|
|
if (sigismember(&blocked, i)) { GC_printf1("%ld ",(long) i); }
|
|
}
|
|
GC_printf0("\n");
|
|
}
|
|
|
|
#endif
|
|
|
|
/* Remove the signals that we want to allow in thread stopping */
|
|
/* handler from a set. */
|
|
void GC_remove_allowed_signals(sigset_t *set)
|
|
{
|
|
# ifdef NO_SIGNALS
|
|
if (sigdelset(set, SIGINT) != 0
|
|
|| sigdelset(set, SIGQUIT) != 0
|
|
|| sigdelset(set, SIGABRT) != 0
|
|
|| sigdelset(set, SIGTERM) != 0) {
|
|
ABORT("sigdelset() failed");
|
|
}
|
|
# endif
|
|
|
|
# ifdef MPROTECT_VDB
|
|
/* Handlers write to the thread structure, which is in the heap, */
|
|
/* and hence can trigger a protection fault. */
|
|
if (sigdelset(set, SIGSEGV) != 0
|
|
# ifdef SIGBUS
|
|
|| sigdelset(set, SIGBUS) != 0
|
|
# endif
|
|
) {
|
|
ABORT("sigdelset() failed");
|
|
}
|
|
# endif
|
|
}
|
|
|
|
static sigset_t suspend_handler_mask;
|
|
|
|
word GC_stop_count; /* Incremented at the beginning of GC_stop_world. */
|
|
|
|
#ifdef GC_OSF1_THREADS
|
|
GC_bool GC_retry_signals = TRUE;
|
|
#else
|
|
GC_bool GC_retry_signals = FALSE;
|
|
#endif
|
|
|
|
/*
|
|
* We use signals to stop threads during GC.
|
|
*
|
|
* Suspended threads wait in signal handler for SIG_THR_RESTART.
|
|
* That's more portable than semaphores or condition variables.
|
|
* (We do use sem_post from a signal handler, but that should be portable.)
|
|
*
|
|
* The thread suspension signal SIG_SUSPEND is now defined in gc_priv.h.
|
|
* Note that we can't just stop a thread; we need it to save its stack
|
|
* pointer(s) and acknowledge.
|
|
*/
|
|
|
|
#ifndef SIG_THR_RESTART
|
|
# if defined(GC_HPUX_THREADS) || defined(GC_OSF1_THREADS)
|
|
# ifdef _SIGRTMIN
|
|
# define SIG_THR_RESTART _SIGRTMIN + 5
|
|
# else
|
|
# define SIG_THR_RESTART SIGRTMIN + 5
|
|
# endif
|
|
# else
|
|
# define SIG_THR_RESTART SIGXCPU
|
|
# endif
|
|
#endif
|
|
|
|
sem_t GC_suspend_ack_sem;
|
|
|
|
void GC_suspend_handler(int sig)
|
|
{
|
|
int dummy;
|
|
pthread_t my_thread = pthread_self();
|
|
GC_thread me;
|
|
# ifdef PARALLEL_MARK
|
|
word my_mark_no = GC_mark_no;
|
|
/* Marker can't proceed until we acknowledge. Thus this is */
|
|
/* guaranteed to be the mark_no correspending to our */
|
|
/* suspension, i.e. the marker can't have incremented it yet. */
|
|
# endif
|
|
word my_stop_count = GC_stop_count;
|
|
|
|
if (sig != SIG_SUSPEND) ABORT("Bad signal in suspend_handler");
|
|
|
|
#if DEBUG_THREADS
|
|
GC_printf1("Suspending 0x%lx\n", my_thread);
|
|
#endif
|
|
|
|
me = GC_lookup_thread(my_thread);
|
|
/* The lookup here is safe, since I'm doing this on behalf */
|
|
/* of a thread which holds the allocation lock in order */
|
|
/* to stop the world. Thus concurrent modification of the */
|
|
/* data structure is impossible. */
|
|
if (me -> stop_info.last_stop_count == my_stop_count) {
|
|
/* Duplicate signal. OK if we are retrying. */
|
|
if (!GC_retry_signals) {
|
|
WARN("Duplicate suspend signal in thread %lx\n",
|
|
pthread_self());
|
|
}
|
|
return;
|
|
}
|
|
# ifdef SPARC
|
|
me -> stop_info.stack_ptr = (ptr_t)GC_save_regs_in_stack();
|
|
# else
|
|
me -> stop_info.stack_ptr = (ptr_t)(&dummy);
|
|
# endif
|
|
# ifdef IA64
|
|
me -> backing_store_ptr = (ptr_t)GC_save_regs_in_stack();
|
|
# endif
|
|
|
|
/* Tell the thread that wants to stop the world that this */
|
|
/* thread has been stopped. Note that sem_post() is */
|
|
/* the only async-signal-safe primitive in LinuxThreads. */
|
|
sem_post(&GC_suspend_ack_sem);
|
|
me -> stop_info.last_stop_count = my_stop_count;
|
|
|
|
/* Wait until that thread tells us to restart by sending */
|
|
/* this thread a SIG_THR_RESTART signal. */
|
|
/* SIG_THR_RESTART should be masked at this point. Thus there */
|
|
/* is no race. */
|
|
do {
|
|
me->stop_info.signal = 0;
|
|
sigsuspend(&suspend_handler_mask); /* Wait for signal */
|
|
} while (me->stop_info.signal != SIG_THR_RESTART);
|
|
/* If the RESTART signal gets lost, we can still lose. That should be */
|
|
/* less likely than losing the SUSPEND signal, since we don't do much */
|
|
/* between the sem_post and sigsuspend. */
|
|
/* We'd need more handshaking to work around that, since we don't want */
|
|
/* to accidentally leave a RESTART signal pending, thus causing us to */
|
|
/* continue prematurely in a future round. */
|
|
|
|
#if DEBUG_THREADS
|
|
GC_printf1("Continuing 0x%lx\n", my_thread);
|
|
#endif
|
|
}
|
|
|
|
void GC_restart_handler(int sig)
|
|
{
|
|
pthread_t my_thread = pthread_self();
|
|
GC_thread me;
|
|
|
|
if (sig != SIG_THR_RESTART) ABORT("Bad signal in suspend_handler");
|
|
|
|
/* Let the GC_suspend_handler() know that we got a SIG_THR_RESTART. */
|
|
/* The lookup here is safe, since I'm doing this on behalf */
|
|
/* of a thread which holds the allocation lock in order */
|
|
/* to stop the world. Thus concurrent modification of the */
|
|
/* data structure is impossible. */
|
|
me = GC_lookup_thread(my_thread);
|
|
me->stop_info.signal = SIG_THR_RESTART;
|
|
|
|
/*
|
|
** Note: even if we didn't do anything useful here,
|
|
** it would still be necessary to have a signal handler,
|
|
** rather than ignoring the signals, otherwise
|
|
** the signals will not be delivered at all, and
|
|
** will thus not interrupt the sigsuspend() above.
|
|
*/
|
|
|
|
#if DEBUG_THREADS
|
|
GC_printf1("In GC_restart_handler for 0x%lx\n", pthread_self());
|
|
#endif
|
|
}
|
|
|
|
# ifdef IA64
|
|
# define IF_IA64(x) x
|
|
# else
|
|
# define IF_IA64(x)
|
|
# endif
|
|
/* We hold allocation lock. Should do exactly the right thing if the */
|
|
/* world is stopped. Should not fail if it isn't. */
|
|
void GC_push_all_stacks()
|
|
{
|
|
GC_bool found_me = FALSE;
|
|
int i;
|
|
GC_thread p;
|
|
ptr_t lo, hi;
|
|
/* On IA64, we also need to scan the register backing store. */
|
|
IF_IA64(ptr_t bs_lo; ptr_t bs_hi;)
|
|
pthread_t me = pthread_self();
|
|
|
|
if (!GC_thr_initialized) GC_thr_init();
|
|
#if DEBUG_THREADS
|
|
GC_printf1("Pushing stacks from thread 0x%lx\n", (unsigned long) me);
|
|
#endif
|
|
for (i = 0; i < THREAD_TABLE_SZ; i++) {
|
|
for (p = GC_threads[i]; p != 0; p = p -> next) {
|
|
if (p -> flags & FINISHED) continue;
|
|
if (pthread_equal(p -> id, me)) {
|
|
# ifdef SPARC
|
|
lo = (ptr_t)GC_save_regs_in_stack();
|
|
# else
|
|
lo = GC_approx_sp();
|
|
# endif
|
|
found_me = TRUE;
|
|
IF_IA64(bs_hi = (ptr_t)GC_save_regs_in_stack();)
|
|
} else {
|
|
lo = p -> stop_info.stack_ptr;
|
|
IF_IA64(bs_hi = p -> backing_store_ptr;)
|
|
}
|
|
if ((p -> flags & MAIN_THREAD) == 0) {
|
|
hi = p -> stack_end;
|
|
IF_IA64(bs_lo = p -> backing_store_end);
|
|
} else {
|
|
/* The original stack. */
|
|
hi = GC_stackbottom;
|
|
IF_IA64(bs_lo = BACKING_STORE_BASE;)
|
|
}
|
|
#if DEBUG_THREADS
|
|
GC_printf3("Stack for thread 0x%lx = [%lx,%lx)\n",
|
|
(unsigned long) p -> id,
|
|
(unsigned long) lo, (unsigned long) hi);
|
|
#endif
|
|
if (0 == lo) ABORT("GC_push_all_stacks: sp not set!\n");
|
|
# ifdef STACK_GROWS_UP
|
|
/* We got them backwards! */
|
|
GC_push_all_stack(hi, lo);
|
|
# else
|
|
GC_push_all_stack(lo, hi);
|
|
# endif
|
|
# ifdef IA64
|
|
# if DEBUG_THREADS
|
|
GC_printf3("Reg stack for thread 0x%lx = [%lx,%lx)\n",
|
|
(unsigned long) p -> id,
|
|
(unsigned long) bs_lo, (unsigned long) bs_hi);
|
|
# endif
|
|
if (pthread_equal(p -> id, me)) {
|
|
GC_push_all_eager(bs_lo, bs_hi);
|
|
} else {
|
|
GC_push_all_stack(bs_lo, bs_hi);
|
|
}
|
|
# endif
|
|
}
|
|
}
|
|
if (!found_me && !GC_in_thread_creation)
|
|
ABORT("Collecting from unknown thread.");
|
|
}
|
|
|
|
/* There seems to be a very rare thread stopping problem. To help us */
|
|
/* debug that, we save the ids of the stopping thread. */
|
|
pthread_t GC_stopping_thread;
|
|
int GC_stopping_pid;
|
|
|
|
/* We hold the allocation lock. Suspend all threads that might */
|
|
/* still be running. Return the number of suspend signals that */
|
|
/* were sent. */
|
|
int GC_suspend_all()
|
|
{
|
|
int n_live_threads = 0;
|
|
int i;
|
|
GC_thread p;
|
|
int result;
|
|
pthread_t my_thread = pthread_self();
|
|
|
|
GC_stopping_thread = my_thread; /* debugging only. */
|
|
GC_stopping_pid = getpid(); /* debugging only. */
|
|
for (i = 0; i < THREAD_TABLE_SZ; i++) {
|
|
for (p = GC_threads[i]; p != 0; p = p -> next) {
|
|
if (p -> id != my_thread) {
|
|
if (p -> flags & FINISHED) continue;
|
|
if (p -> stop_info.last_stop_count == GC_stop_count) continue;
|
|
if (p -> thread_blocked) /* Will wait */ continue;
|
|
n_live_threads++;
|
|
#if DEBUG_THREADS
|
|
GC_printf1("Sending suspend signal to 0x%lx\n", p -> id);
|
|
#endif
|
|
|
|
result = pthread_kill(p -> id, SIG_SUSPEND);
|
|
switch(result) {
|
|
case ESRCH:
|
|
/* Not really there anymore. Possible? */
|
|
n_live_threads--;
|
|
break;
|
|
case 0:
|
|
break;
|
|
default:
|
|
ABORT("pthread_kill failed");
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return n_live_threads;
|
|
}
|
|
|
|
/* Caller holds allocation lock. */
|
|
void GC_stop_world()
|
|
{
|
|
int i;
|
|
int n_live_threads;
|
|
int code;
|
|
|
|
#if DEBUG_THREADS
|
|
GC_printf1("Stopping the world from 0x%lx\n", pthread_self());
|
|
#endif
|
|
|
|
/* Make sure all free list construction has stopped before we start. */
|
|
/* No new construction can start, since free list construction is */
|
|
/* required to acquire and release the GC lock before it starts, */
|
|
/* and we have the lock. */
|
|
# ifdef PARALLEL_MARK
|
|
GC_acquire_mark_lock();
|
|
GC_ASSERT(GC_fl_builder_count == 0);
|
|
/* We should have previously waited for it to become zero. */
|
|
# endif /* PARALLEL_MARK */
|
|
++GC_stop_count;
|
|
n_live_threads = GC_suspend_all();
|
|
|
|
if (GC_retry_signals) {
|
|
unsigned long wait_usecs = 0; /* Total wait since retry. */
|
|
# define WAIT_UNIT 3000
|
|
# define RETRY_INTERVAL 100000
|
|
for (;;) {
|
|
int ack_count;
|
|
|
|
sem_getvalue(&GC_suspend_ack_sem, &ack_count);
|
|
if (ack_count == n_live_threads) break;
|
|
if (wait_usecs > RETRY_INTERVAL) {
|
|
int newly_sent = GC_suspend_all();
|
|
|
|
# ifdef CONDPRINT
|
|
if (GC_print_stats) {
|
|
GC_printf1("Resent %ld signals after timeout\n",
|
|
newly_sent);
|
|
}
|
|
# endif
|
|
sem_getvalue(&GC_suspend_ack_sem, &ack_count);
|
|
if (newly_sent < n_live_threads - ack_count) {
|
|
WARN("Lost some threads during GC_stop_world?!\n",0);
|
|
n_live_threads = ack_count + newly_sent;
|
|
}
|
|
wait_usecs = 0;
|
|
}
|
|
usleep(WAIT_UNIT);
|
|
wait_usecs += WAIT_UNIT;
|
|
}
|
|
}
|
|
for (i = 0; i < n_live_threads; i++) {
|
|
if (0 != (code = sem_wait(&GC_suspend_ack_sem))) {
|
|
GC_err_printf1("Sem_wait returned %ld\n", (unsigned long)code);
|
|
ABORT("sem_wait for handler failed");
|
|
}
|
|
}
|
|
# ifdef PARALLEL_MARK
|
|
GC_release_mark_lock();
|
|
# endif
|
|
#if DEBUG_THREADS
|
|
GC_printf1("World stopped from 0x%lx\n", pthread_self());
|
|
#endif
|
|
GC_stopping_thread = 0; /* debugging only */
|
|
}
|
|
|
|
/* Caller holds allocation lock, and has held it continuously since */
|
|
/* the world stopped. */
|
|
void GC_start_world()
|
|
{
|
|
pthread_t my_thread = pthread_self();
|
|
register int i;
|
|
register GC_thread p;
|
|
register int n_live_threads = 0;
|
|
register int result;
|
|
|
|
# if DEBUG_THREADS
|
|
GC_printf0("World starting\n");
|
|
# endif
|
|
|
|
for (i = 0; i < THREAD_TABLE_SZ; i++) {
|
|
for (p = GC_threads[i]; p != 0; p = p -> next) {
|
|
if (p -> id != my_thread) {
|
|
if (p -> flags & FINISHED) continue;
|
|
if (p -> thread_blocked) continue;
|
|
n_live_threads++;
|
|
#if DEBUG_THREADS
|
|
GC_printf1("Sending restart signal to 0x%lx\n", p -> id);
|
|
#endif
|
|
|
|
result = pthread_kill(p -> id, SIG_THR_RESTART);
|
|
switch(result) {
|
|
case ESRCH:
|
|
/* Not really there anymore. Possible? */
|
|
n_live_threads--;
|
|
break;
|
|
case 0:
|
|
break;
|
|
default:
|
|
ABORT("pthread_kill failed");
|
|
}
|
|
}
|
|
}
|
|
}
|
|
#if DEBUG_THREADS
|
|
GC_printf0("World started\n");
|
|
#endif
|
|
}
|
|
|
|
void GC_stop_init() {
|
|
struct sigaction act;
|
|
|
|
if (sem_init(&GC_suspend_ack_sem, 0, 0) != 0)
|
|
ABORT("sem_init failed");
|
|
|
|
act.sa_flags = SA_RESTART;
|
|
if (sigfillset(&act.sa_mask) != 0) {
|
|
ABORT("sigfillset() failed");
|
|
}
|
|
GC_remove_allowed_signals(&act.sa_mask);
|
|
/* SIG_THR_RESTART is set in the resulting mask. */
|
|
/* It is unmasked by the handler when necessary. */
|
|
act.sa_handler = GC_suspend_handler;
|
|
if (sigaction(SIG_SUSPEND, &act, NULL) != 0) {
|
|
ABORT("Cannot set SIG_SUSPEND handler");
|
|
}
|
|
|
|
act.sa_handler = GC_restart_handler;
|
|
if (sigaction(SIG_THR_RESTART, &act, NULL) != 0) {
|
|
ABORT("Cannot set SIG_THR_RESTART handler");
|
|
}
|
|
|
|
/* Inititialize suspend_handler_mask. It excludes SIG_THR_RESTART. */
|
|
if (sigfillset(&suspend_handler_mask) != 0) ABORT("sigfillset() failed");
|
|
GC_remove_allowed_signals(&suspend_handler_mask);
|
|
if (sigdelset(&suspend_handler_mask, SIG_THR_RESTART) != 0)
|
|
ABORT("sigdelset() failed");
|
|
|
|
/* Check for GC_RETRY_SIGNALS. */
|
|
if (0 != GETENV("GC_RETRY_SIGNALS")) {
|
|
GC_retry_signals = TRUE;
|
|
}
|
|
if (0 != GETENV("GC_NO_RETRY_SIGNALS")) {
|
|
GC_retry_signals = FALSE;
|
|
}
|
|
# ifdef CONDPRINT
|
|
if (GC_print_stats && GC_retry_signals) {
|
|
GC_printf0("Will retry suspend signal if necessary.\n");
|
|
}
|
|
# endif
|
|
}
|
|
|
|
#endif
|