Fix/re2 wasm heap leak#210
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re2-wasm has a fixed 16 MB WASM linear-memory heap with no real free(): every `new RE2(pattern, flags)` permanently consumes a few KB regardless of whether the JS object is later GC'd. After enough compiles the heap is full and any further call aborts with `Cannot enlarge memory arrays to size 16781312 bytes (OOM)`. Reproducer: compiling the same trivial pattern 2965 times in a loop is enough to OOM on a fresh Node process. In production tx.fhir.org hit this via repeated $validate-code calls against the IPS lab-observations ValueSet, whose LOINC `CLASS regex` filter is recompiled per call. Cache compiled RE2 objects by (pattern, flags). Same pattern -> single compile -> single leak. Does not fix the underlying leak; a proper fix is to replace re2-wasm with the native `re2` package, which has real free() semantics.
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https://chat.fhir.org/#narrow/channel/179252-IG-creation/topic/crash.20tx.2Efhir.2Eorg.3F/with/594892934
re2-wasm has a fixed 16 MB WASM linear-memory heap with no real free():
every
new RE2(pattern, flags)permanently consumes a few KB regardless of whether the JS object is later GC'd. After enough compiles the heap is full and any further call aborts withCannot enlarge memory arrays to size 16781312 bytes (OOM).Reproducer: compiling the same trivial pattern 2965 times in a loop is enough to OOM on a fresh Node process. In production tx.fhir.org hit this via repeated $validate-code calls against the IPS lab-observations ValueSet, whose LOINC
CLASS regexfilter is recompiled per call.Cache compiled RE2 objects by (pattern, flags). Same pattern -> single compile -> single leak. Does not fix the underlying leak;
a proper fix is to replace re2-wasm with the native
re2package, which has real free() semantics.