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n-api: reduce gc finalization stress

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https://github.com/nodejs/node/pull/24494 fixed a crash
but resulted in increased stress on gc finalization. A leak
was reported in https://github.com/nodejs/node/issues/26667 which
we are still investigating. As part of this investigation I
realized we can optimize to reduce amount of deferred finalization.
Regardless of the root cause of the leak this should be a
good optimization. It also resolves the leak for the case being
reported in #26667. The OP in 26667 has confirmed that he can
still recreate the original problem that 24494 fixed and that
the fix still works with this optimization

PR-URL: https://github.com/nodejs/node/pull/27085
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
This commit is contained in:
Michael Dawson 2019-04-04 10:24:21 -04:00 committed by Daniel Bevenius
parent b925379f50
commit ff89670902
1 changed files with 9 additions and 7 deletions
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16
src/js_native_api_v8.cc
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@ -227,10 +227,11 @@ class Reference : private Finalizer {
// from one of Unwrap or napi_delete_reference. // from one of Unwrap or napi_delete_reference.
// //
// When it is called from Unwrap or napi_delete_reference we only // When it is called from Unwrap or napi_delete_reference we only
// want to do the delete if the finalizer has already run, // want to do the delete if the finalizer has already run or
// cannot have been queued to run (ie the reference count is > 0),
// otherwise we may crash when the finalizer does run. // otherwise we may crash when the finalizer does run.
// If the finalizer has not already run delay the delete until // If the finalizer may have been queued and has not already run
// the finalizer runs by not doing the delete // delay the delete until the finalizer runs by not doing the delete
// and setting _delete_self to true so that the finalizer will // and setting _delete_self to true so that the finalizer will
// delete it when it runs. // delete it when it runs.
// //
@ -238,13 +239,14 @@ class Reference : private Finalizer {
// the finalizer and _delete_self is set. In this case we // the finalizer and _delete_self is set. In this case we
// know we need to do the deletion so just do it. // know we need to do the deletion so just do it.
static void Delete(Reference* reference) { static void Delete(Reference* reference) {
if ((reference->_delete_self) || (reference->_finalize_ran)) { if ((reference->RefCount() != 0) ||
(reference->_delete_self) ||
(reference->_finalize_ran)) {
delete reference; delete reference;
} else { } else {
// reduce the reference count to 0 and defer until // defer until finalizer runs as
// finalizer runs // it may alread be queued
reference->_delete_self = true; reference->_delete_self = true;
while (reference->Unref() != 0) {}
} }
} }