> On May 24, 2021, at 09:22, Bob Jolliffe <bobjolliffe@gmail.com> wrote:
>
> It is hard to say as it only happens for 30s couple of times per day.
> Everything does return to normal after the blocking transaction is
> committed. It could be a disk thing or even a network issue (the java
> app is on a different machine to the db). But I never saw
> transactions blocked in commit before so was wondering if there is any
> rational set of reasons why it might do that.
One thing you can check is to turn off synchronous_commit (understanding the possibility of "time loss" in the event of
asystem crash). If that mitigates the problem, the issue is likely the I/O subsystem blocking during the fsync()
operation.