Parallel is a container task - it can contain other Ant tasks. Each nested +task within the parallel task will be executed in its own thread.
+ +Parallel tasks have a number of uses in an Ant build file including: +
Care must be taken when using multithreading to ensure the tasks within the +threads do not interact. For example, two javac compile tasks which write +classes into the same destination directory may interact where one tries to +read a class for depenency information while the other task is writing the +class file. Be sure to avoid these types of interactions within a +<parallel> task
+ +The parallel task has no attributes and does not support any nested +elements apart from Ant tasks. Any valid Ant task may be embedded within a +parallel task, including other parallel tasks.
+ +Note that 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 any of the tasks within the <parallel> task fails, the remaining +tasks in other threads will continue to run until all threads have completed. +In this sitiuation, the parallel task will also fail.
+ ++<parallel> + <wlrun ...> + <sequential> + <sleep seconds="30"/> + <junit ...> + <wlstop/> + </sequential> +</parallel> ++
This example represents a typical pattern for testing a server application. +In one thread the server is started (the wlrun task). The other thread consists +of a three tasks which are performed in sequence. The sleep task is used to +give the server time to come up. Another task which is capabale of validating +that the server is available could be used in place of the sleep task. The +test harness is then run. Once the tests are complete, the server is stopped +(using wlstop in this example), allowing both threads to complete. The +parallel task will also complete at this time and the build will then +continue.
+ ++<parallel> + <javac ...> <!-- compiler servlet code --> + <wljspc ...> <!-- precompile JSPs --> +</parallel> ++ +
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. As +noted above, you 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.
+Copyright © 2000,2001 Apache Software Foundation. All rights +Reserved.
+ + + diff --git a/docs/manual/coretasklist.html b/docs/manual/coretasklist.html index 674b63fe4..cab1b77a2 100644 --- a/docs/manual/coretasklist.html +++ b/docs/manual/coretasklist.html @@ -52,6 +52,7 @@ Mail