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diff --git a/framework/src/ant/apache-ant-1.9.6/manual/Tasks/parallel.html b/framework/src/ant/apache-ant-1.9.6/manual/Tasks/parallel.html deleted file mode 100644 index 362daf37..00000000 --- a/framework/src/ant/apache-ant-1.9.6/manual/Tasks/parallel.html +++ /dev/null @@ -1,235 +0,0 @@ -<!-- - Licensed to the Apache Software Foundation (ASF) under one or more - contributor license agreements. See the NOTICE file distributed with - this work for additional information regarding copyright ownership. - The ASF licenses this file to You under the Apache License, Version 2.0 - (the "License"); you may not use this file except in compliance with - the License. You may obtain a copy of the License at - - http://www.apache.org/licenses/LICENSE-2.0 - - Unless required by applicable law or agreed to in writing, software - distributed under the License is distributed on an "AS IS" BASIS, - WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. - See the License for the specific language governing permissions and - limitations under the License. ---> -<html> - -<head> -<meta http-equiv="Content-Language" content="en-us"> -<link rel="stylesheet" type="text/css" href="../stylesheets/style.css"> -<title>Parallel Task</title> -</head> - -<body> - -<h2>Parallel</h2> -<h3>Description</h3> -<p> - Executes nested tasks in parallel with no guarantees of thread safety. - Every task will run in its own thread, with the likelihood of - concurrency problems scaling with the number of CPUs on the host system. -</p> -<p><b>Warning:</b> While the Apache Ant core is believed to be thread safe, no such - guarantees are made about tasks, which are not tested for thread safety during - Ant's test process. - Third party tasks may or may not be thread safe, and some of Ant's core tasks, such as - <code><javac></code> are definitely not re-entrant. This is because they use libraries that - were never designed to be used in a multithreaded environment. -</p> -<p> - The primary use case for <code><parallel></code> is to run external programs - such as an application server, and the JUnit or TestNG test suites at the - same time. Anyone trying to run large Ant task sequences in parallel, such - as javadoc and javac at the same time, is implicitly taking on the task - of identifying and fixing all concurrency bugs the tasks that they run. - -</p> -<p> - Accordingly, while this task has uses, it should be considered an advanced - task which should be used in certain batch-processing or testing situations, - rather than an easy trick to speed up build times on a multiway CPU. -</p> - -<h3>Parameters</h3> -<table border="1" cellpadding="2" cellspacing="0"> - <tr> - <td valign="top"><b>Attribute</b></td> - <td valign="top"><b>Description</b></td> - <td align="center" valign="top"><b>Required</b></td> - </tr> - <tr> - <td valign="top">threadCount</td> - <td valign="top">Maximum numbers of thread to use.</td> - <td align="center" valign="top">No</td> - </tr> - <tr> - <td valign="top">threadsPerProcessor</td> - <td valign="top">Maximum number of threads to use per available processor -(Java 1.4+)</td> - <td align="center" valign="top">No, defers to threadCount</td> - </tr> - <tr> - <td valign="top">timeout</td> - <td valign="top">Number of milliseconds before execution is terminated</td> - <td align="center" valign="top">No</td> - </tr> - <tr> - <td valign="top">failonany</td> - <td valign="top">If any of the nested tasks fails, execution of the task completes - at that point without waiting for any other tasks to complete.</td> - <td align="center" valign="top">No, default is false.</td> - </tr> - <tr> - <td valign="top">pollInterval</td> - <td valign="top">Currently has no effect</td> - <td align="center" valign="top">No, default is 1000</td> - </tr> -</table> - -<p>Parallel tasks have a number of uses in an Ant build file including:</p> -<ul> -<li>Taking advantage of available processing resources to execute external - programs simultaneously.</li> -<li>Testing servers, where the server can be run in one thread and the test -harness is run in another thread.</li> -</ul> - -<p>Any valid Ant task may be embedded within a -parallel task, including other parallel tasks, though there is no guarantee that -the tasks will be thread safe in such an environment.</p> - -<p>While the tasks within the parallel task are being run, the main -thread will be blocked waiting for all the child threads to complete. If -execution is terminated by a timeout or a nested task failure when the -<code>failonany</code> -flag is set, the parallel task will complete without waiting for other nested -tasks to complete in other threads. -</p> - -<p>If any of the tasks within the <code><parallel></code> task fails and failonany is -not set, the remaining tasks in other threads will continue to run until -all threads have completed. In this situation, the parallel task will also fail.</p> - -<p>The parallel task may be combined with the <a href="sequential.html"> -sequential</a> task to define sequences of tasks to be executed on each thread -within the parallel block</p> - -<p>The <code>threadCount</code> attribute can be used to place a maximum number of available -threads for the execution. When not present all child tasks will be executed at -once. When present then the maximum number of concurrently executing tasks will -not exceed the number of threads specified. Furthermore, each task will be -started in the order they are given. But no guarantee is made as to the speed -of execution or the order of completion of the tasks, only that each will be -started before the next.<p> - -<p>If you are using Java 1.4 or later you can also use the <code>threadsPerProcessor</code> -and the number of available threads will be the stated multiple of the number of -processors (there is no affinity to a particular processor however). This will -override the value in <code>threadCount</code>. If <code>threadsPerProcessor</code> -is specified on any older JVM, then the value in <code>threadCount</code> will be used as is.</p> - -<p>When using <code>threadCount</code> and <code>threadsPerProcessor</code> - care should be taken to ensure that the build does not deadlock. - This can be caused by tasks such as <code>waitfor</code> - taking up all available threads before the tasks that would unlock the - <code>waitfor</code> -would occur. This is not a replacement for Java Language level thread -semantics and is best used for "embarassingly parallel" tasks.</p> - - -<h3>Parameters specified as nested elements</h3> - -<h4>daemons</h4> -<p> -The parallel task supports a <code><daemons></code> nested element. This is a list of tasks -which are to be run in parallel daemon threads. The parallel task will not wait for -these tasks to complete. Being daemon threads, however, they will not prevent Ant from -completing, whereupon the threads are terminated. Failures in daemon threads which -occur before the parallel task itself finishes will be reported and can cause -parallel to throw an exception. Failures which occur after parallel has completed are not -reported. -</p> - -<p>Daemon tasks can be used, for example, to start test servers which might not be easily -terminated from Ant. By using <code><daemons></code> such servers do not halt the build. -</p> - - -<h3>Examples</h3> -<pre> -<parallel> - <wlrun ... > - <sequential> - <sleep seconds="30"/> - <junit fork="true" forkmode="once" ... > - <wlstop/> - </sequential> -</parallel> -</pre> -<p>This example represents a typical pattern for testing a server application. -In one thread the server is started (the <code><wlrun></code> task). -The other thread consists -of a three tasks which are performed in sequence. The <code><sleep></code> task is used to -give the server time to come up. Another task which is capable of validating -that the server is available could be used in place of the <code><sleep></code> task. The -<code><junit></code> test harness then runs, again in its own JVM. Once the tests are complete, the server is stopped -(using <code><wlstop></code> in this example), allowing both threads to complete. The -<code><parallel></code> task will also complete at this time and the build will then -continue.</p> - -<pre> -<parallel> - <javac fork="true"...> <!-- compiler servlet code --> - <wljspc ...> <!-- precompile JSPs --> -</parallel> -</pre> - -<p>This example shows two independent tasks being run to achieve better -resource utilization during the build. In this instance, some servlets are being -compiled in one thead and a set of JSPs is being precompiled in another. Developers -need to be careful that the two tasks are independent, both in -terms of their dependencies and in terms of their potential interactions in -Ant's external environment. Here we set <code>fork="true"</code> for the -<code><javac></code> task, so that it runs in a new process; -if the <code><wljspc></code> task used the javac compiler in-VM -(it may), concurrency problems may arise. -</p> - -<pre> - <macrodef name="dbpurge"> - <attribute file="file"/> - <sequential> - <java jar="utils/dbpurge.jar" fork="true" > - <arg file="@{file} /> - </java> - </sequential> -</macrodef> - -<parallel threadCount="4"> - <dbpurge file="db/one" /> - <dbpurge file="db/two" /> - <dbpurge file="db/three" /> - <dbpurge file="db/four" /> - <dbpurge file="db/five" /> - <dbpurge file="db/six" /> - <dbpurge file="db/seven" /> - <dbpurge file="db/eight" /> - <!-- repeated about 40 times --> -</parallel> -</pre> - -<p>This example represents a typical need for use of the threadCount and -threadsPerProcessor attributes. Spinning up all 40 of those tasks could cripple -the system for memory and CPU time. By limiting the number of -concurrent executions you can reduce contention for CPU, memory and disk IO, -and so actually finish faster. This is also a good -candidate for use of threadCount (and possibly threadsPerProcessor) because -each task is independent (every new JVM is forked) and has no dependencies on -the other tasks.</p> - - -</body> -</html> - |