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fix subprocess checking when the process moves itself to a new group

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Closes PR 11200
This commit is contained in:
Matthew Flatt 2011-01-08 09:48:08 -07:00
parent 8f6acf6aae
commit ea51d32e9d
2 changed files with 64 additions and 50 deletions
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70
src/racket/src/places.c
View File

@ -234,19 +234,22 @@ typedef struct Child_Status {
char is_group;
void *signal_fd;
struct Child_Status *next;
struct Child_Status *next_group; /* see child_group_statuses */
struct Child_Status *next_unused; /* see unused_pid_statuses */
} Child_Status;
SHARED_OK static Child_Status *child_statuses = NULL;
SHARED_OK static mzrt_mutex* child_status_lock = NULL;
SHARED_OK static mzrt_mutex* child_wait_lock = NULL; /* ordered before status lock */
/* When a process for a process group becomes unreachable
before a waitpid() on the process, then we need to keep
waiting on it to let the OS gc the process. Otherwise,
we wait only on processes in the same group as Racket.
/* When the Racket process value for a process in a different group becomes
GC-unreachable before a waitpid() on the process, then we
need to keep waiting on the pid to let the OS gc the process.
This list is especially needed for processes that we create in
their own group, but it's also needed for processes that put
themselves in their own group (which we conservatively assume
can be any child process).
This list is protect by the wait lock. */
SHARED_OK static Child_Status *child_group_statuses = NULL;
SHARED_OK static Child_Status *unused_pid_statuses = NULL;
static void add_group_signal_fd(void *signal_fd);
static void remove_group_signal_fd(void *signal_fd);
@ -270,7 +273,7 @@ static void add_child_status(int pid, int status) {
st->signal_fd = NULL;
st->next = child_statuses;
child_statuses = st;
st->next_group = NULL;
st->next_unused = NULL;
st->unneeded = 0;
st->is_group = 0;
}
@ -317,9 +320,9 @@ static int raw_get_child_status(int pid, int *status, int done_only, int do_remo
int scheme_get_child_status(int pid, int is_group, int *status) {
int found = 0;
if (is_group) {
/* need to specifically try the pid, since we don't
wait on other process groups in the background thread */
/* Check specific pid, in case the child has its own group
(either given by Racket or given to itself): */
{
pid_t pid2;
int status;
@ -361,7 +364,7 @@ int scheme_places_register_child(int pid, int is_group, void *signal_fd, int *st
st->next = child_statuses;
child_statuses = st;
st->next_group = NULL;
st->next_unused = NULL;
if (is_group)
add_group_signal_fd(signal_fd);
@ -375,7 +378,7 @@ static void *mz_proc_thread_signal_worker(void *data) {
int status;
int pid, check_pid, is_group;
sigset_t set;
Child_Status *group_status, *prev_group, *next;
Child_Status *unused_status, *prev_unused, *next;
sigemptyset(&set);
sigaddset(&set, SIGCHLD);
@ -399,14 +402,18 @@ static void *mz_proc_thread_signal_worker(void *data) {
mzrt_mutex_lock(child_wait_lock);
group_status = child_group_statuses;
prev_group = NULL;
unused_status = unused_pid_statuses;
prev_unused = NULL;
do {
if (group_status) {
check_pid = group_status->pid;
if (unused_status) {
/* See unused_pid_statuses above */
check_pid = unused_status->pid;
is_group = 1;
} else {
/* We wait only on processes in the same group as Racket,
because detecting the termination of a group's main process
disables our ability to terminate all processes in the group. */
check_pid = 0; /* => processes in the same group as Racket */
is_group = 0;
}
@ -423,26 +430,26 @@ static void *mz_proc_thread_signal_worker(void *data) {
fprintf(stderr, "unexpected error from waitpid(%d[%d]): %d\n",
check_pid, is_group, errno);
if (is_group) {
prev_group = group_status;
group_status = group_status->next;
prev_unused = unused_status;
unused_status = unused_status->next;
}
}
} else if (pid > 0) {
/* printf("SIGCHILD pid %i with status %i %i\n", pid, status, WEXITSTATUS(status)); */
if (is_group) {
next = group_status->next;
if (prev_group)
prev_group->next_group = next;
next = unused_status->next;
if (prev_unused)
prev_unused->next_unused = next;
else
child_group_statuses = next;
free(group_status);
group_status = next;
unused_pid_statuses = next;
free(unused_status);
unused_status = next;
} else
add_child_status(pid, status);
} else {
if (is_group) {
prev_group = group_status;
group_status = group_status->next;
prev_unused = unused_status;
unused_status = unused_status->next;
}
}
} while ((pid > 0) || is_group);
@ -456,16 +463,17 @@ static void *mz_proc_thread_signal_worker(void *data) {
void scheme_done_with_process_id(int pid, int is_group)
{
Child_Status *st;
int keep_unused = 1; /* assume that any process can be in a new group */
mzrt_mutex_lock(child_wait_lock); /* protects child_group_statuses */
mzrt_mutex_lock(child_wait_lock); /* protects unused_pid_statuses */
mzrt_mutex_lock(child_status_lock);
for (st = child_statuses; st; st = st->next) {
if (st->pid == pid) {
if (!st->done) {
if (is_group) {
st->next_group = child_group_statuses;
child_group_statuses = st;
if (keep_unused) {
st->next_unused = unused_pid_statuses;
unused_pid_statuses = st;
if (st->signal_fd)
remove_group_signal_fd(st->signal_fd);
} else
@ -476,7 +484,7 @@ void scheme_done_with_process_id(int pid, int is_group)
}
}
if (st && (is_group || st->done)) {
if (st && (keep_unused || st->done)) {
/* remove it from normal list: */
raw_get_child_status(pid, NULL, 0, 1, !st->done);
}

42
src/racket/src/port.c
View File

@ -6947,7 +6947,10 @@ static int MyPipe(int *ph, int near_index) {
# define GC_write_barrier(x) /* empty */
#endif
SHARED_OK static void *unused_groups;
/* See `unused_pid_statuses' in "places.c" for
a reminder of why this is needed (in both
implementations): */
SHARED_OK static void *unused_pids;
static int need_to_check_children;
@ -6996,18 +6999,18 @@ static void init_sigchld(void)
static void check_child_done(pid_t pid)
{
pid_t result, check_pid;
int status, is_group;
int status, is_unused;
System_Child *sc, *prev;
void **unused = (void **)unused_groups, **unused_prev = NULL;
void **unused = (void **)unused_pids, **unused_prev = NULL;
if (scheme_system_children) {
do {
if (!pid && unused) {
check_pid = (pid_t)(intptr_t)unused[0];
is_group = 1;
is_unused = 1;
} else {
check_pid = pid;
is_group = 0;
is_unused = 0;
}
do {
@ -7017,14 +7020,14 @@ static void check_child_done(pid_t pid)
} while ((result == -1) && (errno == EINTR));
if (result > 0) {
if (is_group) {
if (is_unused) {
/* done with an inaccessible group id */
void *next;
next = (void **)unused[1];
if (unused_prev)
unused_prev[1] = unused[1];
else
unused_groups = unused[1];
unused_pids = unused[1];
free(unused);
unused = (void **)next;
}
@ -7051,12 +7054,12 @@ static void check_child_done(pid_t pid)
}
}
} else {
if (is_group) {
if (is_unused) {
unused_prev = unused;
unused = unused[1];
}
}
} while ((result > 0) || is_group);
} while ((result > 0) || is_unused);
}
}
@ -7292,7 +7295,9 @@ static int subp_done(Scheme_Object *so)
{
System_Child *sc;
sc = (System_Child *)sp->handle;
check_child_done(sp->is_group ? sp->pid : 0);
/* Check specific pid, in case the child has its own group
(either given by Racket or given to itself): */
check_child_done(sp->pid);
if (sc->done)
child_mref_done(sp);
return sc->done;
@ -7350,7 +7355,7 @@ static Scheme_Object *subprocess_status(int argc, Scheme_Object **argv)
}
# else
System_Child *sc = (System_Child *)sp->handle;
check_child_done(sp->is_group ? sp->pid : 0);
check_child_done(sp->pid);
if (sc->done) {
child_mref_done(sp);
@ -7574,7 +7579,7 @@ static Scheme_Object *subproc_group_on (int argc, Scheme_Object *argv[])
}
#ifdef UNIX_PROCESSES
static void unused_process_group(void *_sp, void *ignored)
static void unused_process_record(void *_sp, void *ignored)
{
Scheme_Subprocess *sp = (Scheme_Subprocess *)_sp;
@ -7582,11 +7587,13 @@ static void unused_process_group(void *_sp, void *ignored)
if (!sp->done)
scheme_done_with_process_id(sp->pid, sp->is_group);
# else
void **unused_group;
unused_group = malloc(sizeof(void *) * 2);
unused_group[0] = (void *)(intptr_t)sp->pid;
unused_group[1] = unused_groups;
if (!((System_Child *)sp->handle)->done) {
void **unused_pid;
unused_pid = malloc(sizeof(void *) * 2);
unused_pid[0] = (void *)(intptr_t)sp->pid;
unused_pid[1] = unused_pids;
need_to_check_children = 1;
}
# endif
}
#endif
@ -8254,8 +8261,7 @@ static Scheme_Object *subprocess(int c, Scheme_Object *args[])
# if defined(WINDOWS_PROCESSES)
scheme_add_finalizer(subproc, close_subprocess_handle, NULL);
# else
if (new_process_group)
scheme_add_finalizer(subproc, unused_process_group, NULL);
scheme_add_finalizer(subproc, unused_process_record, NULL);
# endif
if (SCHEME_TRUEP(cust_mode)) {