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Track Environment fields in heap snapshot? #26776

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joyeecheung opened this issue Mar 19, 2019 · 3 comments
Open

Track Environment fields in heap snapshot? #26776

joyeecheung opened this issue Mar 19, 2019 · 3 comments
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lib / src Issues and PRs related to general changes in the lib or src directory.

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@joyeecheung
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joyeecheung commented Mar 19, 2019 •
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At the moment, the Environment fields are not tracked by the heap snapshot (unless they are referenced by some other objects that implements the MemoryRetainer interface) - for example, you can't see any of the AliasedBuffer in the Environment when looking at a heap snapshot taken after bootstrap. Considering the amount of things we attach to the Environment, it should be pretty useful to track those fields in the heap snapshot instead of keeping them invisible for no particular reason.

I am thinking about having Environment implmement MemoryRetainer, are there any concerns around having it inherit from an abstract class? (considering this is semi-exposed to embedders).
@joyeecheung
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cc @nodejs/embedders

@joyeecheung joyeecheung mentioned this issue Mar 20, 2019
Closed
2 tasks
joyeecheung added a commit that referenced this issue Mar 27, 2019
@joyeecheung
src: move AsyncHooks out of Environment
5197053 
PR-URL: #26824
Refs: #26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
joyeecheung added a commit that referenced this issue Mar 27, 2019
@joyeecheung
src: move AsyncCallbackScope out of Environment
cc7bb85 
PR-URL: #26824
Refs: #26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
joyeecheung added a commit that referenced this issue Mar 27, 2019
@joyeecheung
src: move ImmediateInfo out of Environment
4565698 
PR-URL: #26824
Refs: #26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
joyeecheung added a commit that referenced this issue Mar 27, 2019
@joyeecheung
src: move TickInfo out of Environment
2424661 
PR-URL: #26824
Refs: #26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
joyeecheung added a commit that referenced this issue Mar 27, 2019
@joyeecheung
src: move TrackingTraceStateObserver out of Environment
9f37d3c 
PR-URL: #26824
Refs: #26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
joyeecheung added a commit that referenced this issue Mar 27, 2019
@joyeecheung
src: move ShouldNotAbortOnUncaughtScope out of Environment
9d854fb 
PR-URL: #26824
Refs: #26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
targos pushed a commit to targos/node that referenced this issue Mar 27, 2019
@joyeecheung @targos
src: move AsyncHooks out of Environment
16f90ef 
PR-URL: nodejs#26824
Refs: nodejs#26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
targos pushed a commit to targos/node that referenced this issue Mar 27, 2019
@joyeecheung @targos
src: move AsyncCallbackScope out of Environment
0fa0fe0 
PR-URL: nodejs#26824
Refs: nodejs#26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
targos pushed a commit to targos/node that referenced this issue Mar 27, 2019
@joyeecheung @targos
src: move ImmediateInfo out of Environment
4999a89 
PR-URL: nodejs#26824
Refs: nodejs#26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
targos pushed a commit to targos/node that referenced this issue Mar 27, 2019
@joyeecheung @targos
src: move TickInfo out of Environment
9d600a3 
PR-URL: nodejs#26824
Refs: nodejs#26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
targos pushed a commit to targos/node that referenced this issue Mar 27, 2019
@joyeecheung @targos
src: move TrackingTraceStateObserver out of Environment
2e2efdd 
PR-URL: nodejs#26824
Refs: nodejs#26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
targos pushed a commit to targos/node that referenced this issue Mar 27, 2019
@joyeecheung @targos
src: move ShouldNotAbortOnUncaughtScope out of Environment
41db3e4 
PR-URL: nodejs#26824
Refs: nodejs#26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
targos pushed a commit that referenced this issue Mar 27, 2019
@joyeecheung @targos
src: move AsyncHooks out of Environment
4af9ff0 
PR-URL: #26824
Refs: #26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
targos pushed a commit that referenced this issue Mar 27, 2019
@joyeecheung @targos
src: move AsyncCallbackScope out of Environment
6de1220 
PR-URL: #26824
Refs: #26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
targos pushed a commit that referenced this issue Mar 27, 2019
@joyeecheung @targos
src: move ImmediateInfo out of Environment
495e5e9 
PR-URL: #26824
Refs: #26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
targos pushed a commit that referenced this issue Mar 27, 2019
@joyeecheung @targos
src: move TickInfo out of Environment
bc69a81 
PR-URL: #26824
Refs: #26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
targos pushed a commit that referenced this issue Mar 27, 2019
@joyeecheung @targos
src: move TrackingTraceStateObserver out of Environment
7e7f077 
PR-URL: #26824
Refs: #26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
targos pushed a commit that referenced this issue Mar 27, 2019
@joyeecheung @targos
src: move ShouldNotAbortOnUncaughtScope out of Environment
f50c9c6 
PR-URL: #26824
Refs: #26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
@joyeecheung joyeecheung mentioned this issue Mar 30, 2019
Closed
3 tasks
joyeecheung added a commit that referenced this issue Apr 4, 2019
@joyeecheung
src: implement MemoryRetainer in Environment
f59ec2a 
This allows us to track the essentially-global objects in
Environment in the heap snapshot. Note that this patch only
tracks the fields that can be tracked correctly. There are
still several types of fields that cannot be tracked:

- v8::Data including v8::Private, v8::ObjectTemplate etc.
- Internal types that do not implement MemoryRetainer yet
- STL containers with MemoryRetainer* inside
- STL containers with numeric types inside that should not have their
  nodes elided e.g. numeric keys in maps.

The `BaseObject`s are now no longer globals. They are tracked
as arguments in CleanupHookCallbacks referenced by the Environment
node. This model is closer to how their lifetime is managed
internally.

To track the per-environment strong persistent properties, this patch
divides them into those that are also `v8::Value` and those that
are just `v8::Data`. The values can be tracked by the current
memory tracker while the data cannot.

This patch also implements the `MemoryRetainer` interface in several
internal classes so that they can be tracked in the heap snapshot.

PR-URL: #27018
Refs: #26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
BethGriggs pushed a commit that referenced this issue Apr 4, 2019
@joyeecheung @BethGriggs
src: implement MemoryRetainer in Environment
2e8bcbb 
This allows us to track the essentially-global objects in
Environment in the heap snapshot. Note that this patch only
tracks the fields that can be tracked correctly. There are
still several types of fields that cannot be tracked:

- v8::Data including v8::Private, v8::ObjectTemplate etc.
- Internal types that do not implement MemoryRetainer yet
- STL containers with MemoryRetainer* inside
- STL containers with numeric types inside that should not have their
  nodes elided e.g. numeric keys in maps.

The `BaseObject`s are now no longer globals. They are tracked
as arguments in CleanupHookCallbacks referenced by the Environment
node. This model is closer to how their lifetime is managed
internally.

To track the per-environment strong persistent properties, this patch
divides them into those that are also `v8::Value` and those that
are just `v8::Data`. The values can be tracked by the current
memory tracker while the data cannot.

This patch also implements the `MemoryRetainer` interface in several
internal classes so that they can be tracked in the heap snapshot.

PR-URL: #27018
Refs: #26776
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: James M Snell <[email protected]>
@gireeshpunathil
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@joyeecheung - will this enable a debugger (like llnode) walk through the reference chains of C++ objects, starting with a JS object? the use case is debugging native memory leaks, that has JS objects as anchors.

@joyeecheung
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@gireeshpunathil I don't think it's going to be useful for llnode, but it adds more information into the heap snapshots (essentially allowing the heap snapshots to track C++ memory as well)

@jasnell jasnell added the lib / src Issues and PRs related to general changes in the lib or src directory. label Jun 26, 2020
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