AlexanderKaraberov edited a comment on issue #2232: Elusive refc binary memory leaks in index_updater and replicator_worker processes URL: https://github.com/apache/couchdb/issues/2232#issuecomment-539110424 Hi @davisp , Thank you for stepping in. Indeed, fix for `couch_replicator_worker` seems to be a neat and quick one especially considering that those processes always hold the biggest number of binary refs. I will definitely try it. Regarding other smaller leaks I was actually not very precise because there are three types of processes which consume less space but due to a sheer amount of them amplified by sharding, they contribute a lot to a total RAM consumed by `beam.smp`. These are notably (sorted by number of binaries freed): 1. `couch_db_updater` 2. `couch_index` 3. `couch_index_updater` I've repeated my tests several times on various production nodes to exclude variance but distribution is almost always the same. When I inspect binaries of the mentioned processes I see a lot of repeated `BinaryId`s: ```erlang {binary,[{139849336815280,30512,304}, {139849336815280,30512,304}, {139849336815280,30512,304}, {139849336815280,30512,304}, {139849336815280,30512,304}, ``` This pattern is very consistent and doesn't look good for me. Typical amount of binaries when I sort by `length(info(binary))` is around 2300-3000. Unfortunately at this moment we are not running a build of BEAM VM with debug symbols therefore I can't use neither `gdb` to print raw content pointed by those `BinaryId`s, nor use `ETP` commands in order to look deeper and actually understand what are those binaries. But perhaps there are some NIFs which I can use leverage for this? (one thing is clear their size is always more than 64 bytes hence we have off-heap ones here). > For the couch_index_updater, is that the gen_server process, or the anonymous worker process actually performing the updates? Hm, it looks like it's a worker process [according to a code here](https://github.com/apache/couchdb/blob/2.3.1/src/couch_index/src/couch_index_updater.erl#L71). But calling info for the process which reclaimed the most binaries I see this: ``` {'$initial_call',{couch_index_updater,init,1}}]}, ``` that's how I deduced it is `couch_index_updater`. Same for `couch_db_updater`. > because that process already invokes garbage collection after every document processed. Yes you [are right](https://github.com/apache/couchdb/blob/2.3.1/src/couch_index/src/couch_index_updater.erl#L182) but perhaps there more places here which need this?
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