[GitHub] [couchdb] janl opened a new pull request #2980: fix: set gen_server:call() timeout to infinity on ioq bypass

[GitBox <gi...@apache.org>]

janl opened a new pull request #2980:
URL: https://github.com/apache/couchdb/pull/2980


   Before the bypass existed, ioq would call `gen_server:call()`
   on hehalf of it calling module with the queueing logic in between.
   
   Commit e641a740 introduced a way to bypass any queues, but the
   delegated `gen_server:call()` there was added without a timeout
   parameter, leading to a default timeout of 5000ms.
   
   A problem manifests here when operations that are sent through
   ioq that take longer than that 5000ms timeout. In practice, these
   operations should be very rare and this timeout should be a help
   on overloaded systems. However, one sure-fire way to cause an issue
   on an otherwise idle machine is raise the max_document_size and
   store unreasonably large documents, think 50MB+ of raw JSON).
   
   Not that we recommend this, but folks have run this fine on 2.x
   before the ioq changes and it isn’t too hard to support here.
   
   By adding an `infinity` timeout delegated `gen_server:call()` in
   the queue bypasse case, this no longer applies.
   
   Thanks to Joan @woahli Touzet, Bob @rnewson Newson and
   Paul @davisp Davis for helping to track this down.
   
   


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[GitHub] [couchdb] janl merged pull request #2980: fix: set gen_server:call() timeout to infinity on ioq bypass

[GitBox <gi...@apache.org>]

janl merged pull request #2980:
URL: https://github.com/apache/couchdb/pull/2980


   


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