Author: Armin Rigo <[email protected]>
Branch:
Changeset: r933:0126f6216527
Date: 2014-03-03 11:01 +0100
http://bitbucket.org/pypy/stmgc/changeset/0126f6216527/
Log: Fix (from demo/demo_random): needs to check more directly if we use
'overflow_number' or not. Otherwise a badly placed major collection
can run minor_collect(commit=false) in this transaction.
diff --git a/c7/stm/core.c b/c7/stm/core.c
--- a/c7/stm/core.c
+++ b/c7/stm/core.c
@@ -331,9 +331,6 @@
assert(STM_PSEGMENT->safe_point == SP_RUNNING);
assert(STM_PSEGMENT->running_pthread == pthread_self());
- bool has_any_overflow_object =
- (STM_PSEGMENT->objects_pointing_to_nursery != NULL);
-
minor_collection(/*commit=*/ true);
s_mutex_lock();
@@ -363,10 +360,11 @@
push_modified_to_other_segments();
/* update 'overflow_number' if needed */
- if (has_any_overflow_object) {
+ if (STM_PSEGMENT->overflow_number_has_been_used) {
highest_overflow_number += GCFLAG_OVERFLOW_NUMBER_bit0;
assert(highest_overflow_number != 0); /* XXX else, overflow! */
STM_PSEGMENT->overflow_number = highest_overflow_number;
+ STM_PSEGMENT->overflow_number_has_been_used = false;
}
/* send what is hopefully the correct signals */
diff --git a/c7/stm/core.h b/c7/stm/core.h
--- a/c7/stm/core.h
+++ b/c7/stm/core.h
@@ -97,6 +97,7 @@
transaction is done, but only if we actually overflowed any
object; otherwise, no object has got this number. */
uint32_t overflow_number;
+ bool overflow_number_has_been_used;
/* The marker stored in the global 'write_locks' array to mean
"this segment has modified this old object". */
diff --git a/c7/stm/nursery.c b/c7/stm/nursery.c
--- a/c7/stm/nursery.c
+++ b/c7/stm/nursery.c
@@ -248,6 +248,11 @@
dprintf(("minor_collection commit=%d\n", (int)commit));
STM_PSEGMENT->minor_collect_will_commit_now = commit;
+ if (!commit) {
+ /* 'STM_PSEGMENT->overflow_number' is used now by this collection,
+ in the sense that it's copied to the overflow objects */
+ STM_PSEGMENT->overflow_number_has_been_used = true;
+ }
/* We need this to track the large overflow objects for a future
commit. We don't need it if we're committing now. */
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