root@pgload05g ~/tmp/postgresql # git branch * master root@pgload05g ~/tmp/postgresql # git rev-parse HEAD 2195c5afaabd4d794c8bbf1bf10d8e4fe54b6145 root@pgload05g ~/tmp/postgresql # cat bisect_test.sh #!/bin/bash su - postgres -c "/usr/lib/postgresql/9.6/bin/pg_ctl -D /dev/shm/pg/9.6/ stop -m fast" >/dev/null 2>&1 || true rm -rf /dev/shm/pg/9.6/* ./configure --prefix=/usr/lib/postgresql/9.6 --enable-debug >/dev/null || exit 125 make clean >/dev/null || exit 125 make -j 32 >/dev/null 2>&1 || exit 125 make install >/dev/null || exit 125 make -j 32 -C contrib >/dev/null 2>&1 || exit 125 make -C contrib install >/dev/null || exit 125 su - postgres -c "/usr/lib/postgresql/9.6/bin/initdb -D /dev/shm/pg/9.6/" >/dev/null 2>&1 || exit 125 echo "local all all trust" >/dev/shm/pg/9.6/pg_hba.conf echo "host all all 127.0.0.1/32 trust" >>/dev/shm/pg/9.6/pg_hba.conf echo "host all all ::1/128 trust" >>/dev/shm/pg/9.6/pg_hba.conf su - postgres -c '/usr/lib/postgresql/9.6/bin/pg_ctl -D /dev/shm/pg/9.6/ -o "-p 5434" start' >/dev/null 2>&1 || exit 125 sleep 3 su - postgres -c "/usr/lib/postgresql/9.6/bin/pgbench -i -s 100 'host=localhost port=6432 dbname=pg96'" >/dev/null 2>&1 || exit 125 sleep 3 TPS=`su - postgres -c "/usr/lib/postgresql/9.5/bin/pgbench -U postgres -T 60 -j 64 -c 64 -S -n 'host=localhost port=6432 dbname=pg96'" | awk '/excluding connections establishing/ {print $3}' | cut -f1 -d\.` REV=`git rev-parse --short HEAD` echo "$REV $TPS" >>/tmp/bisect96.log if [ "$TPS" -lt 55000 ]; then exit 0 else exit 1 fi root@pgload05g ~/tmp/postgresql # git bisect run ./bisect_test.sh running ./bisect_test.sh Bisecting: 455 revisions left to test after this (roughly 9 steps) [7caaeaf3607fae91318f24debce3dc017ca299a3] Link libpq after libpgfeutils to satisfy Windows linker. running ./bisect_test.sh Bisecting: 227 revisions left to test after this (roughly 8 steps) [9def031bd2821f35b5f506260d922482648a8bb0] Add more tests for commit_timestamp feature running ./bisect_test.sh Bisecting: 113 revisions left to test after this (roughly 7 steps) [e01157500f26342bf4f067a4eb1e45ab9a3cd410] Include portability/mem.h into fd.c for MAP_FAILED. running ./bisect_test.sh Bisecting: 56 revisions left to test after this (roughly 6 steps) [61d2ebdbf9155d80f83281d8c5729c8f8f0949bc] Fix a typo running ./bisect_test.sh Bisecting: 28 revisions left to test after this (roughly 5 steps) [b6afae71aaf6d2df76d0a0a77c8b630220a01ec1] Use %option bison-bridge in psql/pgbench lexers. running ./bisect_test.sh Bisecting: 14 revisions left to test after this (roughly 4 steps) [384dfbde19330541f7fb487f9352949aa06c812e] Fix unsafe use of strtol() on a non-null-terminated Text datum. running ./bisect_test.sh Bisecting: 6 revisions left to test after this (roughly 3 steps) [92b7902deb3155f6975f33e8b6c8be4d9d066172] Clean up some Coverity complaints about commit 0bf3ae88af330496. running ./bisect_test.sh Bisecting: 6 revisions left to test after this (roughly 3 steps) [98a64d0bd713cb89e61bef6432befc4b7b5da59e] Introduce WaitEventSet API. running ./bisect_test.sh Bisecting: 1 revision left to test after this (roughly 1 step) [326d73c86fda407a810675c3b5a48e0a0cc992f5] Second attempt at fixing MSVC build for 68ab8e8ba4a471d9. running ./bisect_test.sh Bisecting: 0 revisions left to test after this (roughly 0 steps) [72e2d21c1249b674496f97cd6009c0bda62f6b4d] Combine win32 and unix latch implementations. running ./bisect_test.sh 98a64d0bd713cb89e61bef6432befc4b7b5da59e is the first bad commit commit 98a64d0bd713cb89e61bef6432befc4b7b5da59e Author: Andres Freund Date: Mon Mar 21 09:56:39 2016 +0100 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 :100755 100755 c10d9549a40951293f16ff058bf077bcddd0bb99 24655dc09614ee72f882abad90a0d071a1e5f51e M configure :100644 100644 47d0f584deda36025cdf0f83252e5976986531e9 c564a7695fa917e664f5c5676c8dc95468fad4e5 M configure.in :040000 040000 3e57535f13f005a4b8e4e606cab91b1f93cad048 b9d1d96a88cd9cfd0ad0a6f98cd36938762bfb57 M src bisect run success root@pgload05g ~/tmp/postgresql # cat /tmp/bisect96.log 65c5fcd 35783 7caaeaf 71532 9def031 36279 e011575 36386 61d2ebd 35791 b6afae7 35288 384dfbd 71557 98a64d0 70223 326d73c 35029 72e2d21 33649 root@pgload05g ~/tmp/postgresql #