org.jgroups.util.ThreadCreator Maven / Gradle / Ivy
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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
package org.jgroups.util;
import org.jgroups.logging.Log;
import org.jgroups.logging.LogFactory;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.util.concurrent.*;
/**
* @author Bela Ban
* @since Helper class to create regular or virtual threads. Virtual threads are not supported for versions
* less than Java 17.
*/
public class ThreadCreator {
private static final Log LOG=LogFactory.getLog(ThreadCreator.class);
private static final MethodHandles.Lookup LOOKUP;
private static final String OF_VIRTUAL_NAME="java.lang.Thread$Builder$OfVirtual";
private static final Class OF_VIRTUAL_CLASS;
private static final MethodHandle OF_VIRTUAL;
private static final MethodHandle CREATE_VTHREAD;
private static final MethodHandle EXECUTORS_NEW_VIRTUAL_THREAD_FACTORY;
static {
LOOKUP=MethodHandles.publicLookup();
OF_VIRTUAL_CLASS=getOfVirtualClass();
OF_VIRTUAL=getOfVirtualHandle();
CREATE_VTHREAD=getCreateVThreadHandle();
EXECUTORS_NEW_VIRTUAL_THREAD_FACTORY=getNewVirtualThreadFactoryHandle();
}
public static boolean hasVirtualThreads() {
return CREATE_VTHREAD != null;
}
protected static MethodHandle getCreateVThreadHandle() {
MethodType type=MethodType.methodType(Thread.class, Runnable.class);
try {
return LOOKUP.findVirtual(OF_VIRTUAL_CLASS, "unstarted", type);
}
catch(Exception ex) {
LOG.debug("%s.unstarted() not found, trying Thread.newThread() (jdk 15/16)", OF_VIRTUAL_NAME);
}
// try Thread.newThread(String name, int characteristics, Runnable task) in JDKs 15 & 16
type=MethodType.methodType(Thread.class, String.class, int.class, Runnable.class);
try {
return LOOKUP.findStatic(Thread.class, "newThread", type);
}
catch(Exception ex) {
LOG.debug("Thread.newThread() not found, falling back to regular threads");
}
return null;
}
protected static Class getOfVirtualClass() {
try {
return Util.loadClass(OF_VIRTUAL_NAME, (Class)null);
}
catch(ClassNotFoundException e) {
LOG.debug("class %s not found", OF_VIRTUAL_NAME);
return null;
}
}
protected static MethodHandle getOfVirtualHandle() {
try {
return OF_VIRTUAL_CLASS != null?
LOOKUP.findStatic(Thread.class, "ofVirtual", MethodType.methodType(OF_VIRTUAL_CLASS)) : null;
}
catch(Exception e) {
return null;
}
}
protected static MethodHandle getNewVirtualThreadFactoryHandle() {
MethodType type=MethodType.methodType(ExecutorService.class);
String[] names={
"newVirtualThreadPerTaskExecutor", // jdk 18-21
"newVirtualThreadExecutor", // jdk 17
"newUnboundedVirtualThreadExecutor" // jdk 15 & 16
};
for(int i=0; i < names.length; i++) {
try {
return LOOKUP.findStatic(Executors.class, names[i], type);
}
catch(Exception e) {
String next=(i+1) < names.length? names[i+1] : "regular thread pool";
LOG.debug("%s not found, falling back to %s", names[i], next);
}
}
return null;
}
public static Thread createThread(Runnable r, String name, boolean daemon, boolean virtual) {
if(!virtual || CREATE_VTHREAD == null) {
Thread t=new Thread(r, name);
t.setDaemon(daemon);
return t;
}
// Thread.ofVirtual().unstarted()
try {
Object of=OF_VIRTUAL.invoke();
Thread t=(Thread)CREATE_VTHREAD.invokeWithArguments(of, r);
t.setName(name);
return t;
}
catch(Throwable t) {
}
// Thread.newThread(String name, int characteristics, Runnable task) in JDKs 15 & 16
try {
return (Thread)CREATE_VTHREAD.invokeExact(name, 1, r);
}
catch(Throwable ex) {
}
return new Thread(r, name);
}
public static ExecutorService createThreadPool(int min_threads, int max_threads, long keep_alive_time,
boolean virtual_threads, Log log) {
return createThreadPool(min_threads, max_threads, keep_alive_time, "abort", new SynchronousQueue<>(),
new DefaultThreadFactory("threads", true, true),
virtual_threads, log);
}
public static ExecutorService createThreadPool(int min_threads, int max_threads, long keep_alive_time,
String rejection_policy,
BlockingQueue queue, final ThreadFactory factory,
boolean useVirtualThreads, Log log) {
if(!useVirtualThreads || EXECUTORS_NEW_VIRTUAL_THREAD_FACTORY == null) {
ThreadPoolExecutor pool=new ThreadPoolExecutor(min_threads, max_threads, keep_alive_time,
TimeUnit.MILLISECONDS, queue, factory);
RejectedExecutionHandler handler=Util.parseRejectionPolicy(rejection_policy);
pool.setRejectedExecutionHandler(new ShutdownRejectedExecutionHandler(handler));
if(log != null)
log.debug("thread pool min/max/keep-alive (ms): %d/%d/%d", min_threads, max_threads, keep_alive_time);
return pool;
}
try {
return (ExecutorService)EXECUTORS_NEW_VIRTUAL_THREAD_FACTORY.invokeExact();
}
catch(Throwable t) {
throw new IllegalStateException(String.format("failed to create virtual thread pool: %s", t));
}
}
}