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Fix issue 41311 - Assert failure ephemeral_heap_segment->saved_committed == heap_segment_committed #41441

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merged 6 commits into from
Aug 31, 2020
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Fix issue 41311 - Assert failure ephemeral_heap_segment->saved_committed == heap_segment_committed #41441

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3d639f2
delete backport.yml so I can push to master
PeterSolMS Aug 21, 2020
fb423e8
Fix for issue 41311 - Assert failure ephemeral_heap_segment->saved_co…
PeterSolMS Aug 27, 2020
c78344e
Merge remote-tracking branch 'upstream/master'
PeterSolMS Aug 27, 2020
0fc9aeb
Undo unintended changes
PeterSolMS Aug 27, 2020
39891b2
Merge branch 'master' into Fix_issue_41311
PeterSolMS Aug 27, 2020
e450308
Address code review feedback, fix assert.
PeterSolMS Aug 28, 2020
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14 changes: 12 additions & 2 deletions src/coreclr/src/gc/gc.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5705,6 +5705,7 @@ void gc_heap::gc_thread_function ()
END_TIMING(suspend_ee_during_log);

proceed_with_gc_p = TRUE;
gradual_decommit_in_progress_p = FALSE;

if (!should_proceed_with_gc())
{
Expand Down Expand Up @@ -11506,6 +11507,15 @@ BOOL gc_heap::grow_heap_segment (heap_segment* seg, uint8_t* high_address, bool*

assert (heap_segment_committed (seg) <= heap_segment_reserved (seg));
assert (high_address <= heap_segment_committed (seg));

#ifdef MULTIPLE_HEAPS
// we should never increase committed beyond decommit target when gradual
// decommit is in progress - if we do, this means commit and decommit are
// going on at the same time.
assert (!gradual_decommit_in_progress_p ||
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I must be missing something - isn't decommit_target smaller than committed? we keep shrinking committed till we reach decommit_tagert when we do the decommit steps.

also when gradual_decommit_in_progress_p is TRUE, shouldn't decommit_target always be non NULL?

nit -

        assert (!gradual_decommit_in_progress_p ||
                 (heap_segment_decommit_target (seg) == nullptr) ||
                 (heap_segment_committed (seg) <= heap_segment_decommit_target (seg)));

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For some heaps, decommit_target may be bigger than committed, and that's fine - it just means that we won't decommit.

When gradual_decommit_in_progress_p is TRUE, decommit_target will be non NULL for the ephemeral_heap_segment, but may be NULL for other segments - the condition was meant to filter out the other segments. Now that I think about it, I realize this isn't a good test - I should compare against ephemeral_heap_segment directly. So I fixed the assert as follows:

    // we should never increase committed beyond decommit target when gradual
    // decommit is in progress - if we do, this means commit and decommit are
    // going on at the same time.
    assert (!gradual_decommit_in_progress_p ||
            (seg != ephemeral_heap_segment) ||
            (heap_segment_committed (seg) <= heap_segment_decommit_target (seg)));

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oh right, I was only thinking about eph seg. and yes the point is if we actually need to commit more, the decommit target had better be bigger otherwise we have a problem. thanks! I agree the new assert looks better.

(seg != ephemeral_heap_segment) ||
(heap_segment_committed (seg) <= heap_segment_decommit_target (seg)));
#endif // MULTIPLE_HEAPS
}

return !!ret;
Expand Down Expand Up @@ -32458,7 +32468,7 @@ void gc_heap::trim_youngest_desired_low_memory()

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if (settings.concurrent || use_large_pages_p || settings.pause_mode == pause_no_gc) [](start = 4, length = 83)

nit

if (settings.concurrent || use_large_pages_p || (settings.pause_mode == pause_no_gc))

void gc_heap::decommit_ephemeral_segment_pages()
{
if (settings.concurrent || use_large_pages_p)
if (settings.concurrent || use_large_pages_p || (settings.pause_mode == pause_no_gc))
{
return;
}
Expand Down Expand Up @@ -32497,7 +32507,7 @@ void gc_heap::decommit_ephemeral_segment_pages()
decommit_target += target_decrease * 2 / 3;
}

heap_segment_decommit_target(ephemeral_heap_segment) = decommit_target;
heap_segment_decommit_target (ephemeral_heap_segment) = decommit_target;

#ifdef MULTIPLE_HEAPS
if (decommit_target < heap_segment_committed (ephemeral_heap_segment))
Expand Down