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Add functions to wait for backend termination

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This adds a function, pg_wait_for_backend_termination(), and a new
timeout argument to pg_terminate_backend(), which will wait for the
backend to actually terminate (with or without signaling it to do so
depending on which function is called). The default behaviour of
pg_terminate_backend() remains being timeout=0 which does not waiting.
For pg_wait_for_backend_termination() the default wait is 5 seconds.

Author: Bharath Rupireddy
Reviewed-By: Fujii Masao, David Johnston, Muhammad Usama,
             Hou Zhijie, Magnus Hagander
Discussion: https://postgr.es/m/CALj2ACUBpunmyhYZw-kXCYs5NM+h6oG_7Df_Tn4mLmmUQifkqA@mail.gmail.com
This commit is contained in:
Magnus Hagander
2021-04-08 11:32:14 +02:00
parent fb310f1781
commit aaf0432572
7 changed files with 174 additions and 7 deletions
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30
doc/src/sgml/func.sgml
View File

@@ -24977,7 +24977,7 @@ SELECT collation for ('foo' COLLATE "de_DE");
<indexterm>
<primary>pg_terminate_backend</primary>
</indexterm>
<function>pg_terminate_backend</function> ( <parameter>pid</parameter> <type>integer</type> )
<function>pg_terminate_backend</function> ( <parameter>pid</parameter> <type>integer</type>, <parameter>timeout</parameter> <type>bigint</type> <literal>DEFAULT</literal> <literal>0</literal> )
<returnvalue>boolean</returnvalue>
</para>
<para>
@@ -24986,6 +24986,34 @@ SELECT collation for ('foo' COLLATE "de_DE");
is a member of the role whose backend is being terminated or the
calling role has been granted <literal>pg_signal_backend</literal>,
however only superusers can terminate superuser backends.
</para>
<para>
If <parameter>timeout</parameter> is not specified or zero, this
function returns <literal>true</literal> whether the process actually
terminates or not, indicating only that the sending of the signal was
successful. If the <parameter>timeout</parameter> is specified (in
milliseconds) and greater than zero, the function waits until the
process is actually terminated or until the given time has passed. If
the process is terminated, the function
returns <literal>true</literal>. On timeout a warning is emitted and
<literal>false</literal> is returned.
</para></entry>
</row>
<row>
<entry role="func_table_entry"><para role="func_signature">
<indexterm>
<primary>pg_wait_for_backend_termination</primary>
</indexterm>
<function>pg_wait_for_backend_termination</function> ( <parameter>pid</parameter> <type>integer</type>, <parameter>timeout</parameter> <type>bigint</type> <literal>DEFAULT</literal> <literal>5000</literal> )
<returnvalue>boolean</returnvalue>
</para>
<para>
Waits for the backend process with the specified Process ID to
terminate. If the process terminates before
the <parameter>timeout</parameter> (in milliseconds)
expires, <literal>true</literal> is returned. On timeout, a warning
is emitted and <literal>false</literal> is returned.
</para></entry>
</row>
</tbody>

4
doc/src/sgml/monitoring.sgml
View File

@@ -1585,6 +1585,10 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
<entry>Waiting for subplan nodes of an <literal>Append</literal> plan
node to be ready.</entry>
</row>
<row>
<entry><literal>BackendTermination</literal></entry>
<entry>Waiting for the termination of another backend.</entry>
</row>
<row>
<entry><literal>BackupWaitWalArchive</literal></entry>
<entry>Waiting for WAL files required for a backup to be successfully