Author: Armin Rigo <[email protected]>
Branch: c8-gil-like
Changeset: r1815:48f9b949581f
Date: 2015-06-12 13:39 +0200
http://bitbucket.org/pypy/stmgc/changeset/48f9b949581f/
Log: Tentative fix: remove the two places setting 'TS_NONE' without the
mutex_lock, which creates race conditions.
Move the major collection at commit a bit earlier, at a point where
the transaction being committed is still running like usual.
Commit no longer does a safe_point at the end: if a safe point is
requested, we now signal C_AT_SAFE_POINT but just leave.
diff --git a/c8/stm/core.c b/c8/stm/core.c
--- a/c8/stm/core.c
+++ b/c8/stm/core.c
@@ -324,10 +324,7 @@
/* Don't check this 'cl'. This entry is already checked */
if (STM_PSEGMENT->transaction_state == TS_INEVITABLE) {
- //assert(first_cl->next == INEV_RUNNING);
- /* the above assert may fail when running a major collection
- while the commit of the inevitable transaction is in progress
- and the element is already attached */
+ assert(first_cl->next == INEV_RUNNING);
return true;
}
@@ -606,9 +603,6 @@
if (is_commit) {
/* compare with _validate_and_add_to_commit_log */
- STM_PSEGMENT->transaction_state = TS_NONE;
- STM_PSEGMENT->safe_point = SP_NO_TRANSACTION;
-
list_clear(STM_PSEGMENT->modified_old_objects);
STM_PSEGMENT->last_commit_log_entry = new;
release_modification_lock_wr(STM_SEGMENT->segment_num);
@@ -640,16 +634,15 @@
STM_PSEGMENT->modified_old_objects);
/* compare with _validate_and_attach: */
- STM_PSEGMENT->transaction_state = TS_NONE;
- STM_PSEGMENT->safe_point = SP_NO_TRANSACTION;
+ acquire_modification_lock_wr(STM_SEGMENT->segment_num);
list_clear(STM_PSEGMENT->modified_old_objects);
STM_PSEGMENT->last_commit_log_entry = new;
- usleep(100); //XXX
-
/* do it: */
bool yes = __sync_bool_compare_and_swap(&old->next, INEV_RUNNING, new);
OPT_ASSERT(yes);
+
+ release_modification_lock_wr(STM_SEGMENT->segment_num);
}
else {
_validate_and_attach(new, /*can_sleep=*/true);
@@ -1232,6 +1225,7 @@
{
stm_thread_local_t *tl = STM_SEGMENT->running_thread;
+ assert(_has_mutex());
STM_PSEGMENT->safe_point = SP_NO_TRANSACTION;
STM_PSEGMENT->transaction_state = TS_NONE;
@@ -1242,6 +1236,13 @@
if (tl != NULL)
timing_event(tl, event);
+ /* If somebody is waiting for us to reach a safe point, we simply
+ signal it now and leave this transaction. This should be enough
+ for synchronize_all_threads() to retry and notice that we are
+ no longer SP_RUNNING. */
+ if (STM_SEGMENT->nursery_end != NURSERY_END)
+ cond_signal(C_AT_SAFE_POINT);
+
release_thread_segment(tl);
/* cannot access STM_SEGMENT or STM_PSEGMENT from here ! */
}
@@ -1301,6 +1302,7 @@
assert(!_has_mutex());
assert(STM_PSEGMENT->safe_point == SP_RUNNING);
+ assert(STM_PSEGMENT->transaction_state != TS_NONE);
if (globally_unique_transaction) {
stm_fatalerror("cannot commit between stm_stop_all_other_threads "
"and stm_resume_all_other_threads");
@@ -1308,6 +1310,13 @@
dprintf(("> stm_commit_transaction(external=%d)\n", (int)external));
minor_collection(/*commit=*/ true, external);
+ if (!external && is_major_collection_requested()) {
+ s_mutex_lock();
+ if (is_major_collection_requested()) { /* if still true */
+ major_collection_with_mutex();
+ }
+ s_mutex_unlock();
+ }
push_large_overflow_objects_to_other_segments();
/* push before validate. otherwise they are reachable too early */
@@ -1346,19 +1355,6 @@
invoke_and_clear_user_callbacks(0); /* for commit */
- /* >>>>> there may be a FORK() happening in the safepoint below <<<<<*/
- if (!external) {
- enter_safe_point_if_requested();
- assert(STM_SEGMENT->nursery_end == NURSERY_END);
-
- /* if a major collection is required, do it here */
- if (is_major_collection_requested()) {
- major_collection_with_mutex();
- }
- }
-
-
_verify_cards_cleared_in_all_lists(get_priv_segment(STM_SEGMENT->segment_num));
-
/* done */
stm_thread_local_t *tl = STM_SEGMENT->running_thread;
assert(external == (tl == NULL));
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