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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 12:17:33 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 12:17:33 +0000 |
| commit | 5e45211a64149b3c659b90ff2de6fa982a5a93ed (patch) | |
| tree | 739caf8c461053357daa9f162bef34516c7bf452 /doc/src/sgml/html/libpq-threading.html | |
| parent | Initial commit. (diff) | |
| download | postgresql-15-5e45211a64149b3c659b90ff2de6fa982a5a93ed.tar.xz postgresql-15-5e45211a64149b3c659b90ff2de6fa982a5a93ed.zip | |
Adding upstream version 15.5.upstream/15.5
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'doc/src/sgml/html/libpq-threading.html')
| -rw-r--r-- | doc/src/sgml/html/libpq-threading.html | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/doc/src/sgml/html/libpq-threading.html b/doc/src/sgml/html/libpq-threading.html new file mode 100644 index 0000000..d3132d7 --- /dev/null +++ b/doc/src/sgml/html/libpq-threading.html @@ -0,0 +1,47 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>34.20. Behavior in Threaded Programs</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="libpq-ssl.html" title="34.19. SSL Support" /><link rel="next" href="libpq-build.html" title="34.21. Building libpq Programs" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">34.20. Behavior in Threaded Programs</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="libpq-ssl.html" title="34.19. SSL Support">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="libpq.html" title="Chapter 34. libpq — C Library">Up</a></td><th width="60%" align="center">Chapter 34. <span class="application">libpq</span> — C Library</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="libpq-build.html" title="34.21. Building libpq Programs">Next</a></td></tr></table><hr /></div><div class="sect1" id="LIBPQ-THREADING"><div class="titlepage"><div><div><h2 class="title" style="clear: both">34.20. Behavior in Threaded Programs</h2></div></div></div><a id="id-1.7.3.27.2" class="indexterm"></a><p> + <span class="application">libpq</span> is reentrant and thread-safe by default. + You might need to use special compiler command-line + options when you compile your application code. Refer to your + system's documentation for information about how to build + thread-enabled applications, or look in + <code class="filename">src/Makefile.global</code> for <code class="literal">PTHREAD_CFLAGS</code> + and <code class="literal">PTHREAD_LIBS</code>. This function allows the querying of + <span class="application">libpq</span>'s thread-safe status: + </p><div class="variablelist"><dl class="variablelist"><dt id="LIBPQ-PQISTHREADSAFE"><span class="term"><code class="function">PQisthreadsafe</code><a id="id-1.7.3.27.4.1.1.2" class="indexterm"></a></span></dt><dd><p> + Returns the thread safety status of the + <span class="application">libpq</span> library. +</p><pre class="synopsis"> +int PQisthreadsafe(); +</pre><p> + </p><p> + Returns 1 if the <span class="application">libpq</span> is thread-safe + and 0 if it is not. + </p></dd></dl></div><p> + One thread restriction is that no two threads attempt to manipulate + the same <code class="structname">PGconn</code> object at the same time. In particular, + you cannot issue concurrent commands from different threads through + the same connection object. (If you need to run concurrent commands, + use multiple connections.) + </p><p> + <code class="structname">PGresult</code> objects are normally read-only after creation, + and so can be passed around freely between threads. However, if you use + any of the <code class="structname">PGresult</code>-modifying functions described in + <a class="xref" href="libpq-misc.html" title="34.12. Miscellaneous Functions">Section 34.12</a> or <a class="xref" href="libpq-events.html" title="34.14. Event System">Section 34.14</a>, it's up + to you to avoid concurrent operations on the same <code class="structname">PGresult</code>, + too. + </p><p> + The deprecated functions <a class="xref" href="libpq-cancel.html#LIBPQ-PQREQUESTCANCEL"><code class="function">PQrequestCancel</code></a> and + <a class="xref" href="libpq-exec.html#LIBPQ-PQOIDSTATUS"><code class="function">PQoidStatus</code></a> are not thread-safe and should not be + used in multithread programs. <a class="xref" href="libpq-cancel.html#LIBPQ-PQREQUESTCANCEL"><code class="function">PQrequestCancel</code></a> + can be replaced by <a class="xref" href="libpq-cancel.html#LIBPQ-PQCANCEL"><code class="function">PQcancel</code></a>. + <a class="xref" href="libpq-exec.html#LIBPQ-PQOIDSTATUS"><code class="function">PQoidStatus</code></a> can be replaced by + <a class="xref" href="libpq-exec.html#LIBPQ-PQOIDVALUE"><code class="function">PQoidValue</code></a>. + </p><p> + If you are using Kerberos inside your application (in addition to inside + <span class="application">libpq</span>), you will need to do locking around + Kerberos calls because Kerberos functions are not thread-safe. See + function <code class="function">PQregisterThreadLock</code> in the + <span class="application">libpq</span> source code for a way to do cooperative + locking between <span class="application">libpq</span> and your application. + </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="libpq-ssl.html" title="34.19. SSL Support">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="libpq.html" title="Chapter 34. libpq — C Library">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="libpq-build.html" title="34.21. Building libpq Programs">Next</a></td></tr><tr><td width="40%" align="left" valign="top">34.19. SSL Support </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.5 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 34.21. Building <span class="application">libpq</span> Programs</td></tr></table></div></body></html>
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