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Andres Freund 98a64d0bd7 Introduce WaitEventSet API. ... Commit ac1d794 ("Make idle backends exit if the postmaster dies.") introduced a regression on, at least, large linux systems. Constantly adding the same postmaster_alive_fds to the OSs internal datastructures for implementing poll/select can cause significant contention; leading to a performance regression of nearly 3x in one example. This can be avoided by using e.g. linux' epoll, which avoids having to add/remove file descriptors to the wait datastructures at a high rate. Unfortunately the current latch interface makes it hard to allocate any persistent per-backend resources. Replace, with a backward compatibility layer, WaitLatchOrSocket with a new WaitEventSet API. Users can allocate such a Set across multiple calls, and add more than one file-descriptor to wait on. The latter has been added because there's upcoming postgres features where that will be helpful. In addition to the previously existing poll(2), select(2), WaitForMultipleObjects() implementations also provide an epoll_wait(2) based implementation to address the aforementioned performance problem. Epoll is only available on linux, but that is the most likely OS for machines large enough (four sockets) to reproduce the problem. To actually address the aforementioned regression, create and use a long-lived WaitEventSet for FE/BE communication. There are additional places that would benefit from a long-lived set, but that's a task for another day. Thanks to Amit Kapila, who helped make the windows code I blindly wrote actually work. Reported-By: Dmitry Vasilyev Discussion: CAB-SwXZh44_2ybvS5Z67p_CDz=XFn4hNAD=CnMEF+QqkXwFrGg@mail.gmail.com 20160114143931.GG10941@awork2.anarazel.de		10 years ago
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buffer	Fix typos.	10 years ago
file	Include portability/mem.h into fd.c for MAP_FAILED.	10 years ago
freespace	Update copyright for 2016	10 years ago
ipc	Introduce WaitEventSet API.	10 years ago
large_object	Update copyright for 2016	10 years ago
lmgr	Add idle_in_transaction_session_timeout.	10 years ago
page	Update copyright for 2016	10 years ago
smgr	Allow to trigger kernel writeback after a configurable number of writes.	10 years ago
Makefile	Remove cvs keywords from all files.	15 years ago