[GitHub] nickva opened a new pull request #1597: Allow disabling off-heap messages

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

nickva opened a new pull request #1597: Allow disabling off-heap messages
URL: https://github.com/apache/couchdb/pull/1597
 
 
   ### Description
   
   Off-heap messages is an Erlang 19 feature:
   
   http://erlang.org/doc/man/erlang.html#process_flag_message_queue_data
   
   It is adviseable to use that setting for processes which expect to receive a
   lot of messages. CouchDB sets it for couch_server, couch_log_server and bunch
   of others as well.
   
   In some cases the off-heap behavior could alter the timing of message receives
   and expose subtle bugs that have been lurking in the code for years. Or could
   slightly reduce performance, so a safety measure allow disabling it.
   
   ### How to test
   
   ```
   > config:set("couchdb","enable_off_heap_messages", "false").
   
   > Pid = whereis(couch_server).
   <0.311.0>
   
   > exit(Pid, kill).
   
   > erlang:process_info(whereis(couch_server), message_queue_data).
   {message_queue_data,on_heap}
   
   ```
   
   ### Related
   
    https://github.com/apache/couchdb/pull/1392
   
   
   

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