src: be less conservative in NearHeapLimitCallback #50718
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joyeecheung
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Nov 13, 2023
src/env.cc
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| // can only be restored when the heap usage falls down below the | ||
| // new limit, so in a heap with unbounded growth the isolate | ||
| // may eventually crash with this new limit - effectively raising | ||
| // the heap limit to the new one. | ||
| size_t new_limit = current_heap_limit + max_young_gen_size; | ||
| size_t estimated_overhead = young_gen_size + (old_gen_size / 2); | ||
| size_t new_limit = current_heap_limit + estimated_overhead; |
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Not sure about this formula - maybe we should use inital_heap_limit here as the base instead of avoid unbound growth of the new limit
Previously the callback only considered potential overhead coming from promotion. As it turns out the cache for calculated line ends could also increase heap memory usage during heap snapshot generation. This patch makes the raised limit less conservative using a formula of (young_gen_size + old_gen_size / 2) for the extra leeway given to the heap limit. Drive-by: use uv_get_available_memory() to calculate the memory available to the process directly and print the memory in MB in the debugging logs.
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I believe this is no longer necessary after the changes in v8 https://issues.chromium.org/issues/42204564 that ensures the heap snapshot generation/serialization only use off-heap memory for the heap snapshot itself (need to wait until v8 12.5 update to roll it in though). |
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Actually on macOS, #50711 is still skipped, because of libuv/libuv#3897 |
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Previously the callback only considered potential overhead coming from promotion. As it turns out the cache for calculated line ends could also increase heap memory usage during heap snapshot generation. This patch makes the raised limit less conservative using a formula of (young_gen_size + old_gen_size / 2) for the extra leeway given to the heap limit.
Drive-by: use uv_get_available_memory() to calculate the memory available to the process directly and print the memory in MB in the debugging logs.
Refs: #50711