gen_event: eliminate selective-receive in fetch_msg/6 #6199
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Perform a non-selective receive with timeout, and pass the message to factored-out decode_msg/7, similar to gen_server.
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RaimoNiskanen
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Since the This was once probably just a matter of code style and nobody has happened to detect the performance bug... |
RaimoNiskanen
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Thank you for your pull request. Great finding! |
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Perform a non-selective receive with timeout, and pass the
message to factored-out decode_msg/7, similar to gen_server.
One of our more heavily used
gen_eventservers got into a state of extreme memory consumption and slow processing a couple of times this summer. When I looked into it recently I discovered thatgen_event's fetch-and-dispatch loop performs a selective receive looking forsystemandEXITmessages (without using the ref trick), which could explain the issues.gen_serveralways picks the first message, and I strongly believegen_eventshould do the same.This bug seems to have been there "for ever" -- even R6B0 has this difference between
gen_eventandgen_server.