/usr/lib/swi-prolog/doc/Manual/threads.html

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<H1><A NAME="sec:8"><SPAN class="sec-nr">8</SPAN> <SPAN class="sec-title">Multi-threaded 
applications</SPAN></A></H1>

<A NAME="sec:threads"></A>

<P>SWI-Prolog multithreading is based on standard C-language 
multithreading support. It is not like <EM>ParLog</EM> or other parallel 
implementations of the Prolog language. Prolog threads have their own 
stacks and only share the Prolog <EM>heap</EM>: predicates, records, 
flags and other global non-backtrackable data. SWI-Prolog thread support 
is designed with the following goals in mind.

<P>
<UL class="latex">
<LI><I>Multi-threaded server applications</I><BR>
Todays computing services often focus on (internet) server applications. 
Such applications often have need for communication between services 
and/or fast non-blocking service to multiple concurrent clients. The 
shared heap provides fast communication and thread creation is 
relatively cheap.<SUP class="fn">81<SPAN class="fn-text">On an dual 
AMD-Athlon 1600, SWI-Prolog 5.1.0 creates and joins 4,957 threads per 
second elapsed time.</SPAN></SUP>

<P>
<LI><I>Interactive applications</I><BR>
Interactive applications often need to perform extensive computation. If 
such computations are executed in a new thread, the main thread can 
process events and allow the user to cancel the ongoing computation. 
User interfaces can also use multiple threads, each thread dealing with 
input from a distinct group of windows. See also <A class="sec" href="mt-xpce.html">section 
8.8</A>.

<P>
<LI><I>Natural integration with foreign code</I><BR>
Each Prolog thread runs in a native thread of the operating system, 
automatically making them cooperate with <EM>MT-safe</EM> foreign-code. 
In addition, any foreign thread can create its own Prolog engine for 
dealing with calling Prolog from C-code.
</UL>

<P>SWI-Prolog multi-threading is based on the POSIX thread standard
<CITE><A class="cite" href="Bibliography.html#Butenhof:1997:PPT">Butenhof, 
1997</A></CITE> used on most popular systems except for MS-Windows. On 
Windows it uses the
<A class="url" href="http://sources.redhat.com/pthreads-win32/">pthread-win32</A> 
emulation of POSIX threads mixed with the Windows native API for 
smoother and faster operation.

<P>
<HR>
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<H2>Section Index</H2>

</CENTER>
<HR>
<DIV class="toc">
<DIV class="toc-h2"><A class="sec" href="threadcreate.html"><SPAN class="sec-nr">8.1</SPAN> <SPAN class="sec-title">Creating 
and destroying Prolog threads</SPAN></A></DIV>
<DIV class="toc-h2"><A class="sec" href="thmonitor.html"><SPAN class="sec-nr">8.2</SPAN> <SPAN class="sec-title">Monitoring 
threads</SPAN></A></DIV>
<DIV class="toc-h2"><A class="sec" href="threadcom.html"><SPAN class="sec-nr">8.3</SPAN> <SPAN class="sec-title">Thread 
communication</SPAN></A></DIV>
<DIV class="toc-h3"><A class="sec" href="threadcom.html#sec:8.3.1"><SPAN class="sec-nr">8.3.1</SPAN> <SPAN class="sec-title">Message 
queues</SPAN></A></DIV>
<DIV class="toc-h3"><A class="sec" href="threadcom.html#sec:8.3.2"><SPAN class="sec-nr">8.3.2</SPAN> <SPAN class="sec-title">Signalling 
threads</SPAN></A></DIV>
<DIV class="toc-h3"><A class="sec" href="threadcom.html#sec:8.3.3"><SPAN class="sec-nr">8.3.3</SPAN> <SPAN class="sec-title">Threads 
and dynamic predicates</SPAN></A></DIV>
<DIV class="toc-h2"><A class="sec" href="threadsync.html"><SPAN class="sec-nr">8.4</SPAN> <SPAN class="sec-title">Thread 
synchronisation</SPAN></A></DIV>
<DIV class="toc-h2"><A class="sec" href="thutil.html"><SPAN class="sec-nr">8.5</SPAN> <SPAN class="sec-title">Thread-support 
library(threadutil)</SPAN></A></DIV>
<DIV class="toc-h3"><A class="sec" href="thutil.html#sec:8.5.1"><SPAN class="sec-nr">8.5.1</SPAN> <SPAN class="sec-title">Debugging 
threads</SPAN></A></DIV>
<DIV class="toc-h3"><A class="sec" href="thutil.html#sec:8.5.2"><SPAN class="sec-nr">8.5.2</SPAN> <SPAN class="sec-title">Profiling 
threads</SPAN></A></DIV>
<DIV class="toc-h2"><A class="sec" href="mtunbound.html"><SPAN class="sec-nr">8.6</SPAN> <SPAN class="sec-title">Unbounded 
thread creation</SPAN></A></DIV>
<DIV class="toc-h2"><A class="sec" href="foreignthread.html"><SPAN class="sec-nr">8.7</SPAN> <SPAN class="sec-title">Multi-threaded 
mixed C and Prolog applications</SPAN></A></DIV>
<DIV class="toc-h3"><A class="sec" href="foreignthread.html#sec:8.7.1"><SPAN class="sec-nr">8.7.1</SPAN> <SPAN class="sec-title">A 
Prolog thread for each native thread (one-to-one)</SPAN></A></DIV>
<DIV class="toc-h3"><A class="sec" href="foreignthread.html#sec:8.7.2"><SPAN class="sec-nr">8.7.2</SPAN> <SPAN class="sec-title">Pooling 
Prolog engines (many-to-many)</SPAN></A></DIV>
<DIV class="toc-h4"><A class="sec" href="foreignthread.html#sec:8.7.2.1"><SPAN class="sec-nr">8.7.2.1</SPAN> <SPAN class="sec-title">Engines 
in single-threaded SWI-Prolog</SPAN></A></DIV>
<DIV class="toc-h2"><A class="sec" href="mt-xpce.html"><SPAN class="sec-nr">8.8</SPAN> <SPAN class="sec-title">Multithreading 
and the XPCE graphics system</SPAN></A></DIV>
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swi-prolog-nox 5.10.4-3ubuntu1 / usr / lib / swi-prolog / doc / Manual / threads.html
