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Remove the garbage collector thread. All resources are freed

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in-line. If the exiting thread cannot release a resource, then
the next thread to exit will release it.
This commit is contained in:
mtm 2004-03-28 14:05:28 +00:00
parent 1425c998a1
commit c715901410
7 changed files with 44 additions and 244 deletions
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1
lib/libthr/thread/Makefile.inc
View File

@ -19,7 +19,6 @@ SRCS+= \
thr_equal.c \
thr_exit.c \
thr_find_thread.c \
thr_gc.c \
thr_getprio.c \
thr_info.c \
thr_init.c \

15
lib/libthr/thread/thr_create.c
View File

@ -62,9 +62,7 @@ int
_pthread_create(pthread_t * thread, const pthread_attr_t * attr,
void *(*start_routine) (void *), void *arg)
{
int f_gc = 0;
int ret = 0;
pthread_t gc_thread;
pthread_t new_thread;
pthread_attr_t pattr;
int flags;
@ -148,12 +146,6 @@ _pthread_create(pthread_t * thread, const pthread_attr_t * attr,
THREAD_LIST_LOCK;
/*
* Check if the garbage collector thread
* needs to be started.
*/
f_gc = (TAILQ_FIRST(&_thread_list) == _thread_initial);
/* Add the thread to the linked list of all threads: */
TAILQ_INSERT_HEAD(&_thread_list, new_thread, tle);
@ -180,13 +172,6 @@ _pthread_create(pthread_t * thread, const pthread_attr_t * attr,
/* Return a pointer to the thread structure: */
(*thread) = new_thread;
/*
* Start a garbage collector thread
* if necessary.
*/
if (f_gc && pthread_create(&gc_thread,NULL, _thread_gc,NULL) != 0)
PANIC("Can't create gc thread");
return (0);
}

48
lib/libthr/thread/thr_exit.c
View File

@ -45,6 +45,8 @@ __weak_reference(_pthread_exit, pthread_exit);
/* thr_exit() */
extern int _thr_exit(void);
static void deadlist_free_threads();
void
_thread_exit(char *fname, int lineno, char *string)
{
@ -171,9 +173,11 @@ _pthread_exit(void *status)
}
/*
* Free any memory allocated for dead threads.
* Add this thread to the list of dead threads, and
* also remove it from the active threads list.
*/
deadlist_free_threads();
TAILQ_INSERT_HEAD(&_dead_list, curthread, dle);
TAILQ_REMOVE(&_thread_list, curthread, tle);
PTHREAD_SET_STATE(curthread, PS_DEAD);
@ -184,20 +188,11 @@ _pthread_exit(void *status)
exitNow = 1;
THREAD_LIST_UNLOCK;
/*
* Signal the garbage collector thread that there is something
* to clean up. But don't allow it to free the memory until after
* it is retired by holding on to the dead list lock.
*/
if (pthread_cond_signal(&_gc_cond) != 0)
PANIC("Cannot signal gc cond");
DEAD_LIST_UNLOCK;
if (exitNow)
exit(0);
DEAD_LIST_UNLOCK;
/*
* This function will not return unless we are the last
* thread, which we can't be because we've already checked
@ -208,3 +203,36 @@ _pthread_exit(void *status)
/* This point should not be reached. */
PANIC("Dead thread has resumed");
}
/*
* Note: this function must be called with the dead thread list
* locked.
*/
static void
deadlist_free_threads()
{
struct pthread *ptd, *ptdTemp;
TAILQ_FOREACH_SAFE(ptd, &_dead_list, dle, ptdTemp) {
/* Don't destroy the initial thread or non-detached threads. */
if (ptd == _thread_initial ||
(ptd->attr.flags & PTHREAD_DETACHED) == 0)
continue;
TAILQ_REMOVE(&_dead_list, ptd, dle);
deadlist_free_onethread(ptd);
}
}
void
deadlist_free_onethread(struct pthread *ptd)
{
if (ptd->attr.stackaddr_attr == NULL && ptd->stack != NULL) {
STACK_LOCK;
_thread_stack_free(ptd->stack, ptd->attr.stacksize_attr,
ptd->attr.guardsize_attr);
STACK_UNLOCK;
}
_retire_thread(ptd->arch_id);
free(ptd);
}

203
lib/libthr/thread/thr_gc.c
View File

@ -1,203 +0,0 @@
/*
* Copyright (c) 1998 John Birrell <jb@cimlogic.com.au>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by John Birrell.
* 4. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*
* Garbage collector thread. Frees memory allocated for dead threads.
*
*/
#include <sys/param.h>
#include <errno.h>
#include <time.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <pthread.h>
#include "thr_private.h"
pthread_addr_t
_thread_gc(pthread_addr_t arg)
{
int f_debug;
int f_done = 0;
int ret;
sigset_t mask;
pthread_t pthread;
pthread_t pthread_cln;
struct timespec abstime;
void *p_stack;
/* Block all signals */
sigfillset(&mask);
pthread_sigmask(SIG_BLOCK, &mask, NULL);
/* Mark this thread as a library thread (not a user thread). */
curthread->flags |= PTHREAD_FLAGS_PRIVATE;
/* Set a debug flag based on an environment variable. */
f_debug = (getenv("LIBC_R_DEBUG") != NULL);
/* Set the name of this thread. */
pthread_set_name_np(curthread,"GC");
while (!f_done) {
/* Check if debugging this application. */
if (f_debug)
/* Dump thread info to file. */
_thread_dump_info();
/*
* Lock the list of dead threads which ensures that
* this thread sees another thread exit:
*/
DEAD_LIST_LOCK;
/* No stack or thread structure to free yet. */
p_stack = NULL;
pthread_cln = NULL;
/* Check if this is the last running thread. */
THREAD_LIST_LOCK;
if (TAILQ_FIRST(&_thread_list) == curthread &&
TAILQ_NEXT(curthread, tle) == NULL)
/*
* This is the last thread, so it can exit
* now.
*/
f_done = 1;
THREAD_LIST_UNLOCK;
/*
* Enter a loop to search for the first dead thread that
* has memory to free.
*/
for (pthread = TAILQ_FIRST(&_dead_list);
p_stack == NULL && pthread_cln == NULL && pthread != NULL;
pthread = TAILQ_NEXT(pthread, dle)) {
/* Don't destroy the initial thread. */
if (pthread == _thread_initial)
continue;
UMTX_LOCK(&pthread->lock);
/*
* Check if the stack was not specified by
* the caller to pthread_create() and has not
* been destroyed yet:
*/
STACK_LOCK;
if (pthread->attr.stackaddr_attr == NULL &&
pthread->stack != NULL) {
_thread_stack_free(pthread->stack,
pthread->attr.stacksize_attr,
pthread->attr.guardsize_attr);
pthread->stack = NULL;
}
STACK_UNLOCK;
/*
* If the thread has not been detached, leave
* it on the dead thread list.
*/
if ((pthread->attr.flags & PTHREAD_DETACHED) == 0) {
UMTX_UNLOCK(&pthread->lock);
continue;
}
/* Remove this thread from the dead list: */
TAILQ_REMOVE(&_dead_list, pthread, dle);
/*
* Point to the thread structure that must
* be freed outside the locks:
*/
pthread_cln = pthread;
UMTX_UNLOCK(&pthread->lock);
/*
* Retire the architecture specific id so it may be
* used for new threads.
*/
_retire_thread(pthread_cln->arch_id);
}
/*
* Check if this is not the last thread and there is no
* memory to free this time around.
*/
if (!f_done && p_stack == NULL && pthread_cln == NULL) {
/* Get the current time. */
if (clock_gettime(CLOCK_REALTIME,&abstime) != 0)
PANIC("gc cannot get time");
/*
* Do a backup poll in 10 seconds if no threads
* die before then.
*/
abstime.tv_sec += 10;
/*
* Wait for a signal from a dying thread or a
* timeout (for a backup poll).
*/
if ((ret = pthread_cond_timedwait(&_gc_cond,
&dead_list_lock, &abstime)) != 0 && ret != ETIMEDOUT) {
_thread_printf(STDERR_FILENO, "ret = %d", ret);
PANIC("gc cannot wait for a signal");
}
}
/* Unlock the garbage collector mutex: */
DEAD_LIST_UNLOCK;
/*
* If there is memory to free, do it now. The call to
* free() might block, so this must be done outside the
* locks.
*/
if (p_stack != NULL)
free(p_stack);
if (pthread_cln != NULL) {
if (pthread_cln->name != NULL) {
/* Free the thread name string. */
free(pthread_cln->name);
}
/*
* Free the memory allocated for the thread
* structure.
*/
free(pthread_cln);
}
}
return (NULL);
}

6
lib/libthr/thread/thr_init.c
View File

@ -224,7 +224,6 @@ init_tdlist(struct pthread *td, int reinit)
}
}
_pthread_mutex_destroy(&dead_list_lock);
_pthread_cond_destroy(&_gc_cond);
} else {
TAILQ_INIT(&_thread_list);
TAILQ_INIT(&_dead_list);
@ -235,11 +234,10 @@ init_tdlist(struct pthread *td, int reinit)
/*
* Initialize the active thread list lock and the
* dead threads list lock & associated condition variable.
* dead threads list lock.
*/
memset(&thread_list_lock, 0, sizeof(spinlock_t));
if (_pthread_mutex_init(&dead_list_lock,NULL) != 0 ||
_pthread_cond_init(&_gc_cond,NULL) != 0)
if (_pthread_mutex_init(&dead_list_lock,NULL) != 0)
PANIC("Failed to initialize garbage collector primitives");
}

6
lib/libthr/thread/thr_join.c
View File

@ -160,12 +160,12 @@ _pthread_join(pthread_t pthread, void **thread_return)
*thread_return = pthread->ret;
}
/* Make the thread collectable by the garbage collector. */
/* Free all remaining memory allocated to the thread. */
pthread->attr.flags |= PTHREAD_DETACHED;
UMTX_UNLOCK(&pthread->lock);
TAILQ_REMOVE(&_dead_list, pthread, dle);
deadlist_free_onethread(pthread);
THREAD_LIST_UNLOCK;
if (pthread_cond_signal(&_gc_cond) != 0)
PANIC("Cannot signal gc cond");
DEAD_LIST_UNLOCK;
}

9
lib/libthr/thread/thr_private.h
View File

@ -719,13 +719,6 @@ SCLASS int _clock_res_usec /* Clock resolution in usec. */
;
#endif
/* Garbage collector condition variable. */
SCLASS pthread_cond_t _gc_cond
#ifdef GLOBAL_PTHREAD_PRIVATE
= NULL
#endif
;
/*
* Array of signal actions for this process.
*/
@ -791,7 +784,6 @@ void _thread_sig_wrapper(int sig, siginfo_t *info, void *context);
void _thread_printf(int fd, const char *, ...);
void _thread_start(void);
void _thread_seterrno(pthread_t, int);
pthread_addr_t _thread_gc(pthread_addr_t);
void _thread_enter_cancellation_point(void);
void _thread_leave_cancellation_point(void);
void _thread_cancellation_point(void);
@ -802,6 +794,7 @@ void _thread_sigblock();
void _thread_sigunblock();
void adjust_prio_inheritance(struct pthread *);
void adjust_prio_protection(struct pthread *);
void deadlist_free_onethread(struct pthread *);
void init_td_common(struct pthread *, struct pthread_attr *, int);
void init_tdlist(struct pthread *, int);
void proc_sigact_copyin(int, const struct sigaction *);