Memory leak fixes #4
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Passing solver.state around as a session.Group results in the solver.state being stored in cache refs, which makes cache ref memory leaks significantly worse. Signed-off-by: Erik Sipsma <erik@sipsma.dev>
Based on testing, each of the three usages of SetFinalizer in buildkit are broken in that they make the memory unfreeable. Most likely this is somehow related to cyclic data structures, but SetFinalizer is very tricky to use correctly so could be something else. Either way, you can empirically see their usage results in unfreeable memory by looking at the heap.alloc.garbage metric when running `viewcore breakdown`. That metric indicates memory in the heap that's not referenced but has not been released. With the SetFinalizers in place, the garbage accumulates to over a GB when running TestModule for a few mins. It never goes down even with manual GC triggers and GOMEMLIMIT settings that force the GC to free as much memory as it can. Removing any one of the SetFinalizers reduces that garbage metric by a few hundred MBs, but removing all of them reduces it down to negligible levels. Signed-off-by: Erik Sipsma <erik@sipsma.dev>
jedevc
approved these changes
Jan 28, 2025
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Side note: I did not end up changing the global
contenthash.defaultManagercache because it doesn't seem to be needed with the other fixes here in place and I don't want to risk performance regressions around that for now.