public final class ThreadManager
extends java.lang.Object
ThreadManager
exposes a ThreadFactory
that allows
App Engine applications to spawn new threads.
Refer to
this discussion of threads for drawbacks of thread usage and possible
alternatives.Constructor and Description |
---|
ThreadManager() |
Modifier and Type | Method and Description |
---|---|
static java.util.concurrent.ThreadFactory |
backgroundThreadFactory()
Returns a
ThreadFactory that will create threads that are
independent of the current request. |
static java.lang.Thread |
createBackgroundThread(java.lang.Runnable runnable)
Create a new
Thread that executes runnable
independent of the current request. |
static java.lang.Thread |
createThreadForCurrentRequest(java.lang.Runnable runnable)
Create a new
Thread that executes runnable for
the duration of the current request. |
static java.util.concurrent.ThreadFactory |
currentRequestThreadFactory()
Returns a
ThreadFactory that will create threads scoped
to the current request. |
public static java.util.concurrent.ThreadFactory currentRequestThreadFactory()
ThreadFactory
that will create threads scoped
to the current request. These threads will be interrupted at the
end of the current request and must complete within the request
deadline. If they fail to, the instance containing them may be
terminated.
The principal reason to use this method is so that the created
threads can make App Engine API calls (com.google.appengine.api.*
).
In general, threads not associated with a request cannot make these API calls.
The returned factory is typically used with a call like
Executors.newCachedThreadPool(ThreadFactory)
.
Do not use the ExecutorService
returned
by this call after the request that created it has completed.
Note that calling ThreadFactory.newThread(java.lang.Runnable)
on the
returned instance may throw any of the unchecked exceptions
mentioned by createBackgroundThread(java.lang.Runnable)
.
java.lang.NullPointerException
- if the calling thread is not associated with a request.public static java.lang.Thread createThreadForCurrentRequest(java.lang.Runnable runnable)
Thread
that executes runnable
for
the duration of the current request. Calling this method is
equivalent to invoking ThreadFactory.newThread(java.lang.Runnable)
on the
ThreadFactory returned from currentRequestThreadFactory()
.
This thread will be interrupted at the end of the current request
and must complete within the request deadline. If it fails to,
the instance containing it may be terminated.java.lang.IllegalStateException
- if you try to create more than 50 threads in a single request.java.lang.NullPointerException
- if the calling thread is not associated with a request.ApiProxy.FeatureNotEnabledException
- If this application
cannot use this feature.public static java.util.concurrent.ThreadFactory backgroundThreadFactory()
ThreadFactory
that will create threads that are
independent of the current request.
This ThreadFactory can currently only be used by backends.
Note that calling ThreadFactory.newThread(java.lang.Runnable)
on the
returned instance may throw any of the unchecked exceptions
mentioned by createBackgroundThread(java.lang.Runnable)
.
public static java.lang.Thread createBackgroundThread(java.lang.Runnable runnable)
Thread
that executes runnable
independent of the current request. Calling this method is
equivalent to invoking ThreadFactory.newThread(java.lang.Runnable)
on the
ThreadFactory returned from backgroundThreadFactory()
.
This method can currently only be used by backends.
ApiProxy.FeatureNotEnabledException
- If this application
cannot use this feature.ApiProxy.CancelledException
- If the request was interrupted
while creating the new thread.ApiProxy.ApiDeadlineExceededException
- If creation of the
new thread took too long.