feat(xsnap): enable gc() in the start compartment #2683
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Modify xsnap.c to add a `gc()` function to the globals of the
initial ("start") Compartment. This function should trigger an immediate,
synchronous, full GC sweep. As a non-standard global, the `gc()` function
will be filtered out of the globals in all child Compartments by SES as
usual.
Note that this changes the snapshot format: heap snapshots written before
this change cannot be read by code after this change. This happens because
`gc()` (which is implemented in C) is a new "callback" (a C function made
available to JS code), which is an "exit" from the reference graph. It must
be recognized during serialization, and re-attached during reload, and xsnap
cannot handle loading snapshots with a different set of exits, even purely
additive changes.
closes #2682
refs #2660
refs #2615
dckc
approved these changes
Mar 19, 2021
| @@ -196,6 +196,23 @@ test('print - start compartment only', async t => { | |||
| t.deepEqual(['no print in Compartment'], opts.messages); | |||
| }); | |||
|
|
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| test('gc - start compartment only', async t => { | |||
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test looks good.
Nice to know the pattern was straightforward to use.
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Modify xsnap.c to add a
gc()function to the globals of theinitial ("start") Compartment. This function should trigger an immediate,
synchronous, full GC sweep. As a non-standard global, the
gc()functionwill be filtered out of the globals in all child Compartments by SES as
usual.
Note that this changes the snapshot format: heap snapshots written before
this change cannot be read by code after this change. This happens because
gc()(which is implemented in C) is a new "callback" (a C function madeavailable to JS code), which is an "exit" from the reference graph. It must
be recognized during serialization, and re-attached during reload, and xsnap
cannot handle loading snapshots with a different set of exits, even purely
additive changes.
closes #2682
refs #2660
refs #2615