| Server IP : 103.119.228.120 / Your IP : 3.138.122.90 Web Server : Apache System : Linux v8.techscape8.com 3.10.0-1160.119.1.el7.tuxcare.els2.x86_64 #1 SMP Mon Jul 15 12:09:18 UTC 2024 x86_64 User : nobody ( 99) PHP Version : 5.6.40 Disable Function : shell_exec,symlink,system,exec,proc_get_status,proc_nice,proc_terminate,define_syslog_variables,syslog,openlog,closelog,escapeshellcmd,passthru,ocinum cols,ini_alter,leak,listen,chgrp,apache_note,apache_setenv,debugger_on,debugger_off,ftp_exec,dl,dll,myshellexec,proc_open,socket_bind,proc_close,escapeshellarg,parse_ini_filepopen,fpassthru,exec,passthru,escapeshellarg,escapeshellcmd,proc_close,proc_open,ini_alter,popen,show_source,proc_nice,proc_terminate,proc_get_status,proc_close,pfsockopen,leak,apache_child_terminate,posix_kill,posix_mkfifo,posix_setpgid,posix_setsid,posix_setuid,dl,symlink,shell_exec,system,dl,passthru,escapeshellarg,escapeshellcmd,myshellexec,c99_buff_prepare,c99_sess_put,fpassthru,getdisfunc,fx29exec,fx29exec2,is_windows,disp_freespace,fx29sh_getupdate,fx29_buff_prepare,fx29_sess_put,fx29shexit,fx29fsearch,fx29ftpbrutecheck,fx29sh_tools,fx29sh_about,milw0rm,imagez,sh_name,myshellexec,checkproxyhost,dosyayicek,c99_buff_prepare,c99_sess_put,c99getsource,c99sh_getupdate,c99fsearch,c99shexit,view_perms,posix_getpwuid,posix_getgrgid,posix_kill,parse_perms,parsesort,view_perms_color,set_encoder_input,ls_setcheckboxall,ls_reverse_all,rsg_read,rsg_glob,selfURL,dispsecinfo,unix2DosTime,addFile,system,get_users,view_size,DirFiles,DirFilesWide,DirPrintHTMLHeaders,GetFilesTotal,GetTitles,GetTimeTotal,GetMatchesCount,GetFileMatchesCount,GetResultFiles,fs_copy_dir,fs_copy_obj,fs_move_dir,fs_move_obj,fs_rmdir,SearchText,getmicrotime MySQL : ON | cURL : ON | WGET : ON | Perl : ON | Python : ON | Sudo : ON | Pkexec : ON Directory : /usr/share/doc/postgresql-9.2.24/html/ |
Upload File : |
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<HTML
><HEAD
><TITLE
>Behavior in Threaded Programs</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
REV="MADE"
HREF="mailto:pgsql-docs@postgresql.org"><LINK
REL="HOME"
TITLE="PostgreSQL 9.2.24 Documentation"
HREF="index.html"><LINK
REL="UP"
TITLE="libpq - C Library"
HREF="libpq.html"><LINK
REL="PREVIOUS"
TITLE="SSL Support"
HREF="libpq-ssl.html"><LINK
REL="NEXT"
TITLE="Building libpq Programs"
HREF="libpq-build.html"><LINK
REL="STYLESHEET"
TYPE="text/css"
HREF="stylesheet.css"><META
HTTP-EQUIV="Content-Type"
CONTENT="text/html; charset=ISO-8859-1"><META
NAME="creation"
CONTENT="2017-11-06T22:43:11"></HEAD
><BODY
CLASS="SECT1"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="5"
ALIGN="center"
VALIGN="bottom"
><A
HREF="index.html"
>PostgreSQL 9.2.24 Documentation</A
></TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="top"
><A
TITLE="SSL Support"
HREF="libpq-ssl.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="top"
><A
HREF="libpq.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="60%"
ALIGN="center"
VALIGN="bottom"
>Chapter 31. <SPAN
CLASS="APPLICATION"
>libpq</SPAN
> - C Library</TD
><TD
WIDTH="20%"
ALIGN="right"
VALIGN="top"
><A
TITLE="Building libpq Programs"
HREF="libpq-build.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="LIBPQ-THREADING"
>31.19. Behavior in Threaded Programs</A
></H1
><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
<TT
CLASS="FILENAME"
>src/Makefile.global</TT
> for <TT
CLASS="LITERAL"
>PTHREAD_CFLAGS</TT
>
and <TT
CLASS="LITERAL"
>PTHREAD_LIBS</TT
>. This function allows the querying of
<SPAN
CLASS="APPLICATION"
>libpq</SPAN
>'s thread-safe status:
</P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><A
NAME="LIBPQ-PQISTHREADSAFE"
></A
><CODE
CLASS="FUNCTION"
>PQisthreadsafe</CODE
>
</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 <TT
CLASS="STRUCTNAME"
>PGconn</TT
> 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
> <TT
CLASS="STRUCTNAME"
>PGresult</TT
> objects are normally read-only after creation,
and so can be passed around freely between threads. However, if you use
any of the <TT
CLASS="STRUCTNAME"
>PGresult</TT
>-modifying functions described in
<A
HREF="libpq-misc.html"
>Section 31.11</A
> or <A
HREF="libpq-events.html"
>Section 31.13</A
>, it's up
to you to avoid concurrent operations on the same <TT
CLASS="STRUCTNAME"
>PGresult</TT
>,
too.
</P
><P
> The deprecated functions <CODE
CLASS="FUNCTION"
>PQrequestCancel</CODE
> and
<CODE
CLASS="FUNCTION"
>PQoidStatus</CODE
> are not thread-safe and should not be
used in multithread programs. <CODE
CLASS="FUNCTION"
>PQrequestCancel</CODE
>
can be replaced by <CODE
CLASS="FUNCTION"
>PQcancel</CODE
>.
<CODE
CLASS="FUNCTION"
>PQoidStatus</CODE
> can be replaced by
<CODE
CLASS="FUNCTION"
>PQoidValue</CODE
>.
</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
><P
> If you experience problems with threaded applications, run the program
in <TT
CLASS="FILENAME"
>src/tools/thread</TT
> to see if your platform has
thread-unsafe functions. This program is run by
<TT
CLASS="FILENAME"
>configure</TT
>, but for binary distributions your
library might not match the library used to build the binaries.
</P
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="libpq-ssl.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="libpq-build.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>SSL Support</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="libpq.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>Building <SPAN
CLASS="APPLICATION"
>libpq</SPAN
> Programs</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>