java 如何根据线程id找到线程

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qingji999 2013-12-06 16:10:57

文章标签 java 如何根据线程id找到线程 文章分类 Java 后端开发

/**
* Copyright 2008, David Robert Nadeau, NadeauSoftware.com
*
* This file is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 2 of
* the License, or (at your option) any later version.
*
* This file is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this file. If not, see
* <a href="http://www.gnu.org/licenses">GNU Licenses</a>.
*/
import java.lang.management.*;
/**
* The ThreadUtilities class provides a collection of static methods
* for listing and finding Thread, ThreadGroup, and ThreadInfo objects.
* <p>
* Please see the accompanying article:
* <a href="http://nadeausoftware.com/articles/2008/04/java_tip_how_list_and_find_threads_and_thread_groups">Java tip: How to list and find threads and thread groups</a>
*
* @author <a href="http://NadeauSoftware.com/">David R. Nadeau</a>
*/
publicfinalclass ThreadUtilities
{
// Dummy constructor
/**
* The ThreadUtilities class cannot be instanced.
*/
private ThreadUtilities( )
{
}
// Thread groups
/**
* The root thread group saved on the first search for it.
* The root group doesn't change for the life of the JVM,
* so once found there is no need to find it again.
*/
privatestatic ThreadGroup rootThreadGroup = null;
/**
* Get the root thread group in the thread group tree.
* Since there is always a root thread group, this
* method never returns null.
*
* @return the root thread group
*/
publicstatic ThreadGroup getRootThreadGroup( )
{
if ( rootThreadGroup != null )
return rootThreadGroup;
ThreadGroup tg = Thread.currentThread( ).getThreadGroup( );
ThreadGroup ptg;
while ( (ptg = tg.getParent( )) != null )
tg = ptg;
rootThreadGroup = tg;
return tg;
}
/**
* Get a list of all thread groups. Since there is
* always at least one thread group (the root), this
* method never returns a null or empty array.
*
* @return an array of thread groups
*/
publicstatic ThreadGroup[] getAllThreadGroups( )
{
final ThreadGroup root = getRootThreadGroup( );
int nAlloc = root.activeGroupCount( );
int n = 0;
ThreadGroup[] groups = null;
do
{
nAlloc *= 2;
groups = new ThreadGroup[ nAlloc ];
n = root.enumerate( groups, true );
} while ( n == nAlloc );
ThreadGroup[] allGroups = new ThreadGroup[n+1];
allGroups[0] = root;
System.arraycopy( groups, 0, allGroups, 1, n );
return allGroups;
}
/**
* Get the thread group with the given name. A null is
* returned if no such group is found. If more than one
* group has the same name, the first one found is returned.
*
* @param name the thread group name to search for
* @return the thread group, or null if not found
* @throws NullPointerException
* if the name is null
*/
publicstatic ThreadGroup getThreadGroup( final String name )
{
if ( name == null )
thrownew NullPointerException( "Null name" );
final ThreadGroup[] groups = getAllThreadGroups( );
for ( ThreadGroup group : groups )
if ( group.getName( ).equals( name ) )
return group;
returnnull;
}
// Threads
/**
* Get a list of all threads. Since there is always at
* least one thread, this method never returns null or
* an empty array.
*
* @return an array of threads
*/
publicstatic Thread[] getAllThreads( )
{
final ThreadGroup root = getRootThreadGroup( );
final ThreadMXBean thbean =
ManagementFactory.getThreadMXBean( );
int nAlloc = thbean.getThreadCount( );
int n = 0;
Thread[] threads = null;
do
{
nAlloc *= 2;
threads = new Thread[ nAlloc ];
n = root.enumerate( threads, true );
} while ( n == nAlloc );
return java.util.Arrays.copyOf( threads, n );
}
/**
* Get a list of all threads in a thread group. An empty
* array is returned if there are no threads in the group.
*
* @param group the thread group to list
* @return an array of threads
* @throws NullPointerException
* if the group is null
*/
publicstatic Thread[] getGroupThreads( final ThreadGroup group )
{
if ( group == null )
thrownew NullPointerException( "Null group" );
int nAlloc = group.activeCount( );
int n = 0;
Thread[] threads = null;
do
{
nAlloc *= 2;
threads = new Thread[ nAlloc ];
n = group.enumerate( threads, false );
} while ( n == nAlloc );
return java.util.Arrays.copyOf( threads, n );
}
/**
* Get a list of all threads in a named thread group.
* A null is returned if the group cannot be found.
* An empty array is returned if there are no threads in
* the group.
*
* @param name the name of the thread group
* @return an array of threads, or null if the
* group is not found
* @throws NullPointerException
* if the name is null
*/
publicstatic Thread[] getGroupThreads( final String name )
{
final ThreadGroup group = getThreadGroup( name );
if ( group == null )
returnnull;
return getGroupThreads( group );
}
/**
* Get a list of all threads, sorted from highest to
* lowest priority. Since there is always at least one
* thread, this method never returns null or an empty
* array. Since threads may change their priority during
* this method's sort, the returned thread list may not be
* correct by the time it is returned.
*
* @return an array of threads
*/
publicstatic Thread[] getAllThreadsPrioritized( )
{
final Thread[] allThreads = getAllThreads( );
java.util.Arrays.sort( allThreads,
new java.util.Comparator<Thread>( )
{
publicint compare( final Thread t1, final Thread t2 )
{ return t2.getPriority( ) - t1.getPriority( ); }
} );
return allThreads;
}
/**
* Get a list of all daemon threads. An empty array is
* returned if there are no daemon threads.
*
* @return an array of daemon threads
*/
publicstatic Thread[] getAllDaemonThreads( )
{
final Thread[] allThreads = getAllThreads( );
final Thread[] daemons = new Thread[allThreads.length];
int nDaemon = 0;
for ( Thread thread : allThreads )
if ( thread.isDaemon( ) )
daemons[nDaemon++] = thread;
return java.util.Arrays.copyOf( daemons, nDaemon );
}
/**
* Get a list of all threads with a given thread state.
* Thread states are defined in the Thread.State enum for
* the Thread class. Principal thread states include
* RUNNABLE, WAITING, TIMED_WAITING, and BLOCKED. An
* empty array is returned if there are no threads in
* the chosen state.
*
* @param state the state to look for
* @return an array of threads in that state
*/
publicstatic Thread[] getAllThreads( final Thread.State state )
{
final Thread[] allThreads = getAllThreads( );
final Thread[] found = new Thread[allThreads.length];
int nFound = 0;
for ( Thread thread : allThreads )
if ( thread.getState( ) == state )
found[nFound++] = thread;
return java.util.Arrays.copyOf( found, nFound );
}
/**
* Get the thread with the given name. A null is returned
* if no such thread is found. If more than one thread has
* the same name, the first one found is returned.
*
* @param name the thread name to search for
* @return the thread, or null if not found
* @throws NullPointerException
* if the name is null
*/
publicstatic Thread getThread( final String name )
{
if ( name == null )
thrownew NullPointerException( "Null name" );
final Thread[] threads = getAllThreads( );
for ( Thread thread : threads )
if ( thread.getName( ).equals( name ) )
return thread;
returnnull;
}
/**
* Get the thread with the given ID. A null is returned
* if no such thread is found.
*
* @param id the thread ID to search for
* @return the thread, or null if not found
*/
publicstatic Thread getThread( finallong id )
{
final Thread[] threads = getAllThreads( );
for ( Thread thread : threads )
if ( thread.getId( ) == id )
return thread;
returnnull;
}
/**
* Get the thread for the given thread info. A null
* is returned if the thread cannot be found.
*
* @param info the thread info to search for
* @return the thread, or null if not found
* @throws NullPointerException
* if info is null
*/
publicstatic Thread getThread( final ThreadInfo info )
{
if ( info == null )
thrownew NullPointerException( "Null info" );
return getThread( info.getThreadId( ) );
}
// ThreadInfo
/**
* Get a list of all thread info objects. Since there is
* always at least one thread running, there is always at
* least one thread info object. This method never returns
* a null or empty array.
*
* @return an array of thread infos
*/
publicstatic ThreadInfo[] getAllThreadInfos( )
{
final ThreadMXBean thbean =
ManagementFactory.getThreadMXBean( );
finallong[] ids = thbean.getAllThreadIds( );
// Get thread info with lock info, when available.
ThreadInfo[] infos;
if ( !thbean.isObjectMonitorUsageSupported( ) ||
!thbean.isSynchronizerUsageSupported( ) )
infos = thbean.getThreadInfo( ids );
else
infos = thbean.getThreadInfo( ids, true, true );
// Clean nulls from array if threads have died.
final ThreadInfo[] notNulls = new ThreadInfo[infos.length];
int nNotNulls = 0;
for ( ThreadInfo info : infos )
if ( info != null )
notNulls[nNotNulls++] = info;
if ( nNotNulls == infos.length )
return infos; // Original had no nulls
return java.util.Arrays.copyOf( notNulls, nNotNulls );
}
/**
* Get the thread info for the thread with the given name.
* A null is returned if no such thread info is found.
* If more than one thread has the same name, the thread
* info for the first one found is returned.
*
* @param name the thread name to search for
* @return the thread info, or null if not found
* @throws NullPointerException
* if the name is null
*/
publicstatic ThreadInfo getThreadInfo( final String name )
{
if ( name == null )
thrownew NullPointerException( "Null name" );
final Thread[] threads = getAllThreads( );
for ( Thread thread : threads )
if ( thread.getName( ).equals( name ) )
return getThreadInfo( thread.getId( ) );
returnnull;
}
/**
* Get the thread info for the thread with the given ID.
* A null is returned if no such thread info is found.
*
* @param id the thread ID to search for
* @return the thread info, or null if not found
* @throws IllegalArgumentException
* if id <= 0
*/
publicstatic ThreadInfo getThreadInfo( finallong id )
{
final ThreadMXBean thbean =
ManagementFactory.getThreadMXBean( );
// Get thread info with lock info, when available.
if ( !thbean.isObjectMonitorUsageSupported( ) ||
!thbean.isSynchronizerUsageSupported( ) )
return thbean.getThreadInfo( id );
final ThreadInfo[] infos = thbean.getThreadInfo(
newlong[] { id }, true, true );
if ( infos.length == 0 )
returnnull;
return infos[0];
}
/**
* Get the thread info for the given thread. A null is
* returned if the thread info cannot be found.
*
* @param thread the thread to search for
* @return the thread info, or null if not found
* @throws NullPointerException
* if thread is null
*/
publicstatic ThreadInfo getThreadInfo( final Thread thread )
{
if ( thread == null )
thrownew NullPointerException( "Null thread" );
return getThreadInfo( thread.getId( ) );
}
// MonitorInfo and LockInfo
/**
* Get the thread holding a lock on the given object.
* A null is returned if there is no such thread.
*
* @param object the object to look for a lock on
* @return the thread holding a lock, or
* null if there is none
* @throws NullPointerException
* if the object is null
*/
publicstatic Thread getLockingThread( final Object object )
{
if ( object == null )
thrownew NullPointerException( "Null object" );
finallong identity = System.identityHashCode( object );
final Thread[] allThreads = getAllThreads( );
ThreadInfo info = null;
MonitorInfo[] monitors = null;
for ( Thread thread : allThreads )
{
info = getThreadInfo( thread.getId( ) );
if ( info == null )
continue;
monitors = info.getLockedMonitors( );
for ( MonitorInfo monitor : monitors )
if ( identity == monitor.getIdentityHashCode( ) )
return thread;
}
returnnull;
}
/**
* Get the thread who's lock is blocking the given thread.
* A null is returned if there is no such thread.
*
* @param blockedThread the blocked thread
* @return the blocking thread, or null if
* there is none
* @throws NullPointerException
* if the blocked thread is null
*/
publicstatic Thread getBlockingThread( final Thread blockedThread )
{
final ThreadInfo info = getThreadInfo( blockedThread );
if ( info == null )
returnnull;
finallong id = info.getLockOwnerId( );
if ( id == -1 )
returnnull;
return getThread( id );
}
}