[GitHub] [couchdb] kocolosk commented on issue #2493: couch_auth_cache creates millions of monitors to _users.couch database which introduces a performance drop

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kocolosk commented on issue #2493: couch_auth_cache creates millions of monitors to _users.couch database which introduces a performance drop
URL: https://github.com/apache/couchdb/issues/2493#issuecomment-578984046
 
 
   Fascinating. You said that 
   
   > When I removed `couch_db:monitor(AuthDb)` line and called `gen_server:call(couch_auth_cache, reinit_cache, infinity).` in a loop in the `remsh` afterwards for the sake of testing it still created all those duplicated monitors.
   
   I can't reproduce that part on master (d59d84ac78e5). If I remove the `couch_db:monitor/1` invocation and call reinit_cache in a loop I only see the one monitor for the file descriptor at any point in time.
   
   If, however, I leave the `couch_db:monitor/1` invocation in place I *do* see monitors piling up against the `couch_db_updater` process when I call reinit in a loop. Is it possible that those monitors were the ones you saw during your debugging, and that the `couch_file` monitors you observed in production have a different root cause?
   
   Taking a step back, it's not at all obvious to me that we still need `couch_auth_cache` as a running service, especially now that the backdoor HTTP port has been removed. I think the `chttpd_auth_cache` module is the one doing the actual user caching. I'd be curious to hear from others on the dev team, but I'm wondering if we can just shut this thing down. Reading through the code it's clear that this module hasn't kept up with the times.

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