On 2021-01-14 19:11, torikoshia wrote:
Since pg_get_target_backend_memory_contexts() waits to dump memory and
it could lead dead lock as below.
- session1
BEGIN; TRUNCATE t;
- session2
BEGIN; TRUNCATE t; -- wait
- session1
SELECT * FROM pg_get_target_backend_memory_contexts(<pid of session
2>); --wait
Thanks for notifying me, Fujii-san.
Attached v8 patch that prohibited calling the function inside
transactions.
Regrettably, this modification could not cope with the advisory lock and
I haven't come up with a good way to deal with it.
It seems to me that the architecture of the requestor waiting for the
dumper leads to this problem and complicates things.
Considering the discussion printing backtrace discussion[1], it seems
reasonable that the requestor just sends a signal and dumper dumps to
the log file.
Since I found a past discussion that was doing exactly what I thought
reasonable[2], I'm going to continue that discussion if there are no
objections.
Any thought?
[1]
https://www.postgresql.org/message-id/flat/CALDaNm3ZzmFS-=r7oduzj7y7bgqv+n06kqyft6c3xzdoknk...@mail.gmail.com
[2]
https://www.postgresql.org/message-id/flat/20171212044330.3nclev2sfrab36tf%40alap3.anarazel.de#6f28be9839c74779ed6aaa75616124f5
Regards,
--
Atsushi Torikoshi
NTT DATA CORPORATION
