issue with host name lookup in PQconnectdb
The problem i am facing is that PQconnectdb is blocking even though i
specified connect_timeout=10. My observation is below.
1. To simulate this issue, i stopped the postgreSQL-x64-9.4 service and
executed my application.
2. host=localhost is used, database present in the same machine.
3. I have a service created by NSSM, created out of my application exe.
4. My application doesn't blocks, the PQconnectDB fails instantaneously but
when ran as a service PQconnectDB blocks. No difference in code and
environment between exe and service.
5. The blocking issue in service gets eliminated when i replace host with
hostaddr=127.0.0.1. I thought maybe DNS lookup was the issue.
With these observation i tried to understand the nature and root cause of
the issue, could someone throw a light on this?
-Dharani
dharani kumar <dharanikumarsrvn@gmail.com> writes:
The problem i am facing is that PQconnectdb is blocking even though i
specified connect_timeout=10. My observation is below.
1. To simulate this issue, i stopped the postgreSQL-x64-9.4 service and
executed my application.
2. host=localhost is used, database present in the same machine.
3. I have a service created by NSSM, created out of my application exe.
4. My application doesn't blocks, the PQconnectDB fails instantaneously but
when ran as a service PQconnectDB blocks. No difference in code and
environment between exe and service.
5. The blocking issue in service gets eliminated when i replace host with
hostaddr=127.0.0.1. I thought maybe DNS lookup was the issue.
AFAIK this is expected behavior: libpq is not able to make its DNS lookups
nonblocking. The hostaddr option was added specifically so there is a way
to make connections without relying on DNS.
regards, tom lane
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