wohali opened a new pull request #763: Reduce default max_dbs_open to 100 URL: https://github.com/apache/couchdb/pull/763 With `q=8` being the default shard setting, and the Linux default of 1024 file handles per process out of the box on virtually every distro, the maximum number of databases an unmodified user environment could conceivably open simultaneously is 128. (Assuming one view/index per database open as well, that number drops to 64.) When we hit these limits (enfile / emfile Erlang errors) CouchDB starts acting very erratically, leading to lots of scary errors and in some cases inconsistent databases. We have a recent report of mem3 dying as a result, which took the ets tables with it - and this occurred with just 32 databases, with multiple views . In another case a user reported pereceived database corruption (which was actually a combination of error reports + app-server layer errors). While we should recommend ulimit/fs.file-max be bumped in production use, and consequently bumping max_dbs_open as well, we should defend against these kinds of errors for users who compile and install from source (our official distribution option). max_dbs_open = 100 makes this kind of error less likely. This also matches our couchdb-documentation repository, which still reflects a setting of 100 and was never updated to match our increased 500 limit. The alternate approach is for us to better handle enfile / emfile errors and react accordingly, but there are are a significant number of touch points in the code where this can cause issues. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
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