svn: E175002: MERGE request on svn/xxx failed: 504 Gateway Time-out. Can't write response to output: Broken pipe - post-commit

Question

Client ERROR:
svn: E175002: Commit failed (details follow):
svn: E175002: MERGE request on '/svn/my_repos/trunk/app' failed: 504 Gateway Time-out
Server ERROR LOG:
[Thu Aug 25 09:24:49.466833 2016] [dav:error] [pid 20669] [client 192.168.2.99:31447] Could not MERGE resource "/svn/my_repos/!svn/txn/68582-1h18" into "/svn/my_repos/trunk/app". [500, #0]
[Thu Aug 25 09:24:49.466882 2016] [dav:error] [pid 20669] [client 192.168.2.99:31447] Error constructing resource list. [500, #32]
[Thu Aug 25 09:24:49.466884 2016] [dav:error] [pid 20669] [client 192.168.2.99:31447] Can't write response to output: Broken pipe [500, #32]

Answer 1

in my case ,there error was caused by post-commit svnsync.
I changed this command:
/usr/bin/svnsync sync --non-interactive --username svnsync --password ****** ${svn_mirror_url}
to run background and redirect stdout and stderr to /dev/null
/usr/bin/svnsync sync --non-interactive --username svnsync --password ****** ${svn_mirror_url} >/dev/null 2>/dev/null &
reference links:
http://subversion.tigris.org/ds/viewMessage.do?dsForumId=1065&viewType=browseAll&dsMessageId=685574#messagefocus
http://stackoverflow.com/questions/4584904/what-causes-the-broken-pipe-error
http://unix.stackexchange.com/questions/60222/why-does-subversion-give-a-broken-pipe-error-when-piped-into-head