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Replace ThreadLocals and add v thread ctx pooling #9

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7d4f081
Replace ThreadLocals
franz1981 May 30, 2023
20ed13d
Add few comments and add pooling of v thread ctx
franz1981 May 30, 2023
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21 changes: 13 additions & 8 deletions vertx-async-await-incubator/src/main/java/io/vertx/await/Async.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@ public class Async {

private final Vertx vertx;
private final boolean useVirtualEventLoopThreads;
private static final String VTHREAD_CTX = "VTHREAD_CTX";

public Async(Vertx vertx) {
this(vertx, false);
Expand All @@ -32,17 +33,21 @@ public Async(Vertx vertx, boolean useVirtualEventLoopThreads) {
* Run a task on a virtual thread
*/
public void run(Handler<Void> task) {
assert !Thread.currentThread().isVirtual();
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I actually expect to be able to call .run from a virtual thread all the time

Context ctx = vertx.getOrCreateContext();
EventLoop eventLoop;
if (ctx.isEventLoopContext()) {
eventLoop = ((ContextInternal)ctx).nettyEventLoop();
} else {
if (!ctx.isEventLoopContext()) {
throw new IllegalStateException();
}
// Scheduler scheduler = useVirtualEventLoopThreads ? new SchedulerImpl(LoomaniaScheduler2.threadFactory(eventLoop)): new SchedulerImpl(SchedulerImpl.DEFAULT_THREAD_FACTORY);
Scheduler scheduler = useVirtualEventLoopThreads ? new EventLoopScheduler(eventLoop) : new DefaultScheduler(DefaultScheduler.DEFAULT_THREAD_FACTORY);
VirtualThreadContext context = VirtualThreadContext.create(vertx, eventLoop, scheduler);
context.runOnContext(task);
var unsafeCtx = (ContextInternal) ctx;
VirtualThreadContext virtualCtx = unsafeCtx.getLocal(VTHREAD_CTX);
if (virtualCtx == null) {
EventLoop eventLoop = unsafeCtx.nettyEventLoop();
// Scheduler scheduler = useVirtualEventLoopThreads ? new SchedulerImpl(LoomaniaScheduler2.threadFactory(eventLoop)): new SchedulerImpl(SchedulerImpl.DEFAULT_THREAD_FACTORY);
Scheduler scheduler = useVirtualEventLoopThreads ? new EventLoopScheduler(eventLoop) : new DefaultScheduler(DefaultScheduler.DEFAULT_THREAD_FACTORY);
virtualCtx = VirtualThreadContext.create(vertx, eventLoop, scheduler);
unsafeCtx.putLocal(VTHREAD_CTX, virtualCtx);
}
virtualCtx.runOnContext(task);
}

private static VirtualThreadContext virtualThreadContext() {
Expand Down
26 changes: 16 additions & 10 deletions vertx-async-await-incubator/src/main/java/io/vertx/await/impl/EventLoopScheduler.java
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Expand Up @@ -52,23 +52,29 @@ private static ThreadFactory threadFactory(Executor carrier) {

private final ThreadFactory threadFactory;
private final LinkedList<Runnable> tasks = new LinkedList<>();
private boolean flag;
private boolean runOnContext;

public EventLoopScheduler(EventLoop carrier) {
this(command -> {
if (carrier.inEventLoop()) {
command.run();
} else {
carrier.execute(command);
}
execute(carrier, command);
});
}

public EventLoopScheduler(Executor carrier) {
private static void execute(EventLoop carrier, Runnable command) {
if (carrier.inEventLoop()) {
command.run();
} else {
carrier.execute(command);
}
}

private EventLoopScheduler(Executor carrier) {
threadFactory = threadFactory(command -> {
if (flag) {
if (runOnContext) {
tasks.addLast(command);
} else {
// "external" continuations are prioritized and placed
// upfront, to be consumed first
tasks.addFirst(command);
}
carrier.execute(() -> {
Expand All @@ -84,11 +90,11 @@ public Consumer<Runnable> unschedule() {

public void execute(Runnable runnable) {
Thread thread = threadFactory.newThread(runnable);
flag = true;
runOnContext = true;
try {
thread.start();
} finally {
flag = false;
runOnContext = false;
}
}
}
61 changes: 29 additions & 32 deletions vertx-async-await-incubator/src/main/java/io/vertx/await/impl/VirtualThreadContext.java
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Expand Up @@ -4,20 +4,10 @@
import io.vertx.core.Context;
import io.vertx.core.Handler;
import io.vertx.core.Vertx;
import io.vertx.core.impl.CloseFuture;
import io.vertx.core.impl.ContextBase;
import io.vertx.core.impl.ContextInternal;
import io.vertx.core.impl.Deployment;
import io.vertx.core.impl.VertxImpl;
import io.vertx.core.impl.VertxInternal;
import io.vertx.core.impl.WorkerPool;
import io.vertx.core.impl.*;

import java.util.Objects;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionStage;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.*;
import java.util.concurrent.locks.Lock;
import java.util.function.Consumer;

Expand All @@ -32,7 +22,11 @@ public static VirtualThreadContext create(Vertx vertx, EventLoop nettyEventLoop,
}

private final Scheduler scheduler;
private final ThreadLocal<Boolean> inThread = new ThreadLocal<>();

// Use this instead of a ThreadLocal because must friendly with Virtual Threads!
// ideally we should use https://github.com/JCTools/JCTools/blob/master/jctools-core/src/main/java/org/jctools/maps/NonBlockingHashMap.java
// which doesn't use any synchronized op!
private final ConcurrentHashSet<Thread> inThread = new ConcurrentHashSet<>();

VirtualThreadContext(VertxInternal vertx,
EventLoop eventLoop,
Expand Down Expand Up @@ -97,38 +91,39 @@ public boolean isWorkerContext() {
private <T> void run(ContextInternal ctx, T value, Handler<T> task) {
Objects.requireNonNull(task, "Task handler must not be null");
scheduler.execute(() -> {
inThread.set(true);
var current = Thread.currentThread();
inThread.add(current);
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I adopted this fix separately in my fork, it's an essential one

try {
ctx.dispatch(value, task);
} finally {
inThread.remove();
inThread.remove(current);
}
});
}

private <T> void execute2(T argument, Handler<T> task) {
if (Context.isOnWorkerThread()) {
inThread.set(true);
try {
task.handle(argument);
} finally {
inThread.remove();
}
handle(argument, task);
} else {
scheduler.execute(() -> {
inThread.set(true);
try {
task.handle(argument);
} finally {
inThread.remove();
}
handle(argument, task);
});
}
}

private <T> void handle(T argument, Handler<T> task) {
var current = Thread.currentThread();
inThread.add(current);
try {
task.handle(argument);
} finally {
inThread.remove(current);
}
}

@Override
public boolean inThread() {
return inThread.get() == Boolean.TRUE;
return inThread.contains(Thread.currentThread());
}

@Override
Expand All @@ -138,7 +133,8 @@ public ContextInternal duplicate() {
}

public void lock(Lock lock) {
inThread.remove();
var current = Thread.currentThread();
inThread.remove(current);
Consumer<Runnable> cont = scheduler.unschedule();
CompletableFuture<Void> latch = new CompletableFuture<>();
try {
Expand All @@ -154,12 +150,13 @@ public void lock(Lock lock) {
} catch (ExecutionException e) {
throwAsUnchecked(e);
} finally {
inThread.set(true);
inThread.add(current);
}
}

public <T> T await(CompletionStage<T> fut) {
inThread.remove();
var current = Thread.currentThread();
inThread.remove(current);
Consumer<Runnable> cont = scheduler.unschedule();
CompletableFuture<T> latch = new CompletableFuture<>();
fut.whenComplete((v, err) -> {
Expand All @@ -175,7 +172,7 @@ public <T> T await(CompletionStage<T> fut) {
throwAsUnchecked(e.getCause());
return null;
} finally {
inThread.set(true);
inThread.add(current);
}
}

Expand Down
19 changes: 19 additions & 0 deletions ...async-await-incubator/src/test/java/io/vertx/await/EventLoopVirtualThreadContextTest.java
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Expand Up @@ -30,4 +30,23 @@ public void testSuspend() {
await();
}

@Test
public void testSuspendFromEventLoop() {
vertx.runOnContext(v0 -> {
async.run(v1 -> {
CompletableFuture<Void> cf = new CompletableFuture<>();
vertx.runOnContext(v2 -> {
cf.complete(null);
});
try {
cf.get(10, TimeUnit.SECONDS);
} catch (Exception e) {
fail(e);
}
testComplete();
});
});
await();
}

}