I have an SML program which sometimes fails while trying to allocate an array of 3 million ints, with the message
Run out of store - interrupting threads
and an exception.
This happens on one of the first substantial allocations in the program, near the start of its run, so there should be space available - and it only happens on occasional runs, and if it doesn't fail, then the rest of the program (which does a lot more work) runs fine.
The exact size of the array being allocated doesn't seem to matter so long as it's reasonably large, but despite this and the fact that it's so early in the program, I haven't yet managed to make a simple test program with a similar allocation pattern that fails.
The situation seems to be the same regardless of whether I use Poly/ML 5.7, 5.8, or current git.
I compared a successful run with an unsuccessful one based on logging in the runtime. In both cases this allocation gets sent for a "quick GC", which returns failure, followed by a full GC, which runs and then either succeeds or fails to establish that there is enough memory available afterwards (via CheckForAllocation).
In the "good" case, when this check comes to AllocHeapSpace, the test "if (space->allocationSpace)" never succeeds and we fall out of the first loop with currentAllocSpace == 0, defaultSpaceSize == 131072, spaceBeforeMinorGC == 120608, and our request for minWords == 3000001 is successfully fielded in the following conditional block.
In the "bad" case, when this check comes to AllocHeapSpace, the "if (space->allocationSpace)" test succeeds once (available == 131070), then we fall out of the first loop with currentAllocSpace == 131072, defaultSpaceSize == 131072, spaceBeforeMinorGC == 120608, the following conditional is not entered, and we return failure from the line at the end of the function, causing the GC to return failure as well.
If I comment out the check
if (currentAllocSpace/* + minWords */ < spaceBeforeMinorGC)
then it apparently always succeeds, but I can see that this is no solution because no GC is happening at all without it...
Any suggestions for what I might look at next?
Chris
