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[GR-44051] Fail at runtime when Loom virtual threads are reachable so that code can probe for it. #5928

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Merged
merged 1 commit into from
Feb 8, 2023
Merged

[GR-44051] Fail at runtime when Loom virtual threads are reachable so that code can probe for it. #5928

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71 changes: 36 additions & 35 deletions substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/thread/ContinuationsFeature.java
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Original file line number Diff line number Diff line change
Expand Up @@ -36,7 +36,9 @@
import com.oracle.svm.core.feature.InternalFeature;
import com.oracle.svm.core.heap.StoredContinuation;
import com.oracle.svm.core.heap.StoredContinuationAccess;
import com.oracle.svm.core.option.SubstrateOptionsParser;
import com.oracle.svm.core.util.UserError;
import com.oracle.svm.core.util.VMError;
import com.oracle.svm.util.ReflectionUtil;

@AutomaticallyRegisteredFeature
Expand All @@ -45,43 +47,52 @@ public class ContinuationsFeature implements InternalFeature {

@Override
public void afterRegistration(AfterRegistrationAccess access) {
final int firstLoomPreviewVersion = 19;
final int lastLoomPreviewVersion = 20;

boolean supportLoom = false;
if (JavaVersionUtil.JAVA_SPEC >= 19) {
boolean haveLoom = false;
try {
haveLoom = (Boolean) Class.forName("jdk.internal.misc.PreviewFeatures")
.getDeclaredMethod("isEnabled").invoke(null);
} catch (ReflectiveOperationException ignored) {
}
if (!haveLoom) {
// Can still get initialized and fail the image build despite substitution, so defer
RuntimeClassInitialization.initializeAtRunTime("jdk.internal.vm.Continuation");
if (JavaVersionUtil.JAVA_SPEC >= firstLoomPreviewVersion) {
boolean haveLoom;
if (JavaVersionUtil.JAVA_SPEC > lastLoomPreviewVersion) {
haveLoom = true;
} else {
try {
haveLoom = (Boolean) Class.forName("jdk.internal.misc.PreviewFeatures")
.getDeclaredMethod("isEnabled").invoke(null);
} catch (ReflectiveOperationException e) {
throw VMError.shouldNotReachHere(e);
}
if (!haveLoom) {
// Defer: can get initialized and fail the image build despite substitution
RuntimeClassInitialization.initializeAtRunTime("jdk.internal.vm.Continuation");
}
}
// Fail if virtual threads are used and runtime compilation is enabled
supportLoom = haveLoom && !DeoptimizationSupport.enabled() && !SubstrateOptions.useLLVMBackend();
}

/*
* Note: missing support for Loom due to preview features being off, runtime compilation, or
* the LLVM backend is reported at runtime to allow probing without failing the image build.
*/
if (supportLoom) {
LoomVirtualThreads vt = new LoomVirtualThreads();
ImageSingletons.add(VirtualThreads.class, vt);
ImageSingletons.add(LoomVirtualThreads.class, vt); // for simpler check in LoomSupport
} else if (SubstrateOptions.SupportContinuations.getValue()) {
if (SubstrateOptions.useLLVMBackend()) {
throw UserError.abort("Virtual threads are not supported together with the LLVM backend.");
if (DeoptimizationSupport.enabled()) {
throw UserError.abort("Option %s is in use, but is not supported together with Truffle JIT compilation.",
SubstrateOptionsParser.commandArgument(SubstrateOptions.SupportContinuations, "+"));
} else if (SubstrateOptions.useLLVMBackend()) {
throw UserError.abort("Option %s is in use, but is not supported together with the LLVM backend.",
SubstrateOptionsParser.commandArgument(SubstrateOptions.SupportContinuations, "+"));
} else if (JavaVersionUtil.JAVA_SPEC == 17) {
if (DeoptimizationSupport.enabled()) {
throw UserError.abort("Virtual threads are enabled, but are currently not supported together with Truffle JIT compilation.");
}
ImageSingletons.add(VirtualThreads.class, new SubstrateVirtualThreads());
} else if (JavaVersionUtil.JAVA_SPEC >= firstLoomPreviewVersion && JavaVersionUtil.JAVA_SPEC <= lastLoomPreviewVersion) {
throw UserError.abort("Virtual threads on JDK %d are supported only with preview features enabled (--enable-preview). Using option %s is unnecessary.",
JavaVersionUtil.JAVA_SPEC, SubstrateOptionsParser.commandArgument(SubstrateOptions.SupportContinuations, "+"));
} else {
/*
* GR-37518: on 11, ForkJoinPool syncs on a String that doesn't have its own monitor
* field, and unparking a virtual thread in additionalMonitorsLock.unlock causes a
* deadlock between carrier thread and virtual thread. 17 uses a ReentrantLock.
*
* We intentionally do not advertise non-Loom continuation support on 17.
*/
throw UserError.abort("Virtual threads are supported only on JDK 19 with preview features enabled (--enable-preview).");
throw UserError.abort("Option %s is in use, but is not supported on JDK %d.",
SubstrateOptionsParser.commandArgument(SubstrateOptions.SupportContinuations, "+"), JavaVersionUtil.JAVA_SPEC);
}
}
finishedRegistration = true;
Expand All @@ -105,11 +116,6 @@ public void beforeAnalysis(BeforeAnalysisAccess access) {
ReflectionUtil.lookupMethod(StoredContinuationAccess.class, "allocate", int.class));
} else {
access.registerReachabilityHandler(a -> abortIfUnsupported(), StoredContinuationAccess.class);
if (JavaVersionUtil.JAVA_SPEC >= 19) {
access.registerReachabilityHandler(a -> abortIfUnsupported(),
ReflectionUtil.lookupMethod(Thread.class, "ofVirtual"),
ReflectionUtil.lookupMethod(Thread.class, "startVirtualThread", Runnable.class));
}
}
}

Expand All @@ -123,11 +129,6 @@ public void beforeCompilation(BeforeCompilationAccess access) {
}

static void abortIfUnsupported() {
if (!Continuation.isSupported()) {
if (DeoptimizationSupport.enabled()) {
throw UserError.abort("Virtual threads are used in code, but are currently not supported together with Truffle JIT compilation.");
}
throw UserError.abort("Virtual threads are used in code, but are not currently available or active. Use JDK 19 with preview features enabled (--enable-preview).");
}
VMError.guarantee(Continuation.isSupported(), "Virtual thread internals are reachable but support is not available or active.");
}
}
30 changes: 25 additions & 5 deletions ...atevm/src/com.oracle.svm.core/src/com/oracle/svm/core/thread/Target_java_lang_Thread.java
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Original file line number Diff line number Diff line change
Expand Up @@ -33,7 +33,6 @@
import java.util.concurrent.ThreadFactory;
import java.util.function.BooleanSupplier;

import com.oracle.svm.util.ReflectionUtil;
import org.graalvm.compiler.api.directives.GraalDirectives;
import org.graalvm.compiler.replacements.ReplacementsUtil;
import org.graalvm.compiler.serviceprovider.JavaVersionUtil;
Expand All @@ -52,6 +51,7 @@
import com.oracle.svm.core.annotate.Substitute;
import com.oracle.svm.core.annotate.TargetClass;
import com.oracle.svm.core.annotate.TargetElement;
import com.oracle.svm.core.deopt.DeoptimizationSupport;
import com.oracle.svm.core.jdk.ContinuationsNotSupported;
import com.oracle.svm.core.jdk.ContinuationsSupported;
import com.oracle.svm.core.jdk.JDK11OrEarlier;
Expand All @@ -63,6 +63,7 @@
import com.oracle.svm.core.jdk.NotLoomJDK;
import com.oracle.svm.core.monitor.MonitorSupport;
import com.oracle.svm.core.util.VMError;
import com.oracle.svm.util.ReflectionUtil;

@TargetClass(Thread.class)
@SuppressWarnings({"unused"})
Expand Down Expand Up @@ -635,17 +636,27 @@ private static void clearInterruptEvent() {
@TargetElement(onlyWith = LoomJDK.class)
public static native Target_java_lang_Thread_Builder ofVirtual();

/** This method being reachable fails the image build, see {@link ContinuationsFeature}. */
@Substitute
@TargetElement(name = "ofVirtual", onlyWith = {JDK19OrLater.class, NotLoomJDK.class})
public static Target_java_lang_Thread_Builder ofVirtualWithoutLoom() {
if (Target_jdk_internal_misc_PreviewFeatures.isEnabled()) {
if (DeoptimizationSupport.enabled()) {
throw new UnsupportedOperationException("Virtual threads are not supported together with Truffle JIT compilation.");
}
if (SubstrateOptions.useLLVMBackend()) {
throw new UnsupportedOperationException("Virtual threads are not supported together with the LLVM backend.");
}
} else {
Target_jdk_internal_misc_PreviewFeatures.ensureEnabled(); // throws
}
throw VMError.shouldNotReachHere();
}

/** This method being reachable fails the image build, see {@link ContinuationsFeature}. */
@Substitute
@TargetElement(onlyWith = {JDK19OrLater.class, NotLoomJDK.class})
static Thread startVirtualThread(Runnable task) {
@TargetElement(name = "startVirtualThread", onlyWith = {JDK19OrLater.class, NotLoomJDK.class})
static Thread startVirtualThreadWithoutLoom(Runnable task) {
Objects.requireNonNull(task);
ofVirtualWithoutLoom(); // throws
throw VMError.shouldNotReachHere();
}

Expand Down Expand Up @@ -783,3 +794,12 @@ interface Target_sun_nio_ch_Interruptible {
@Alias
void interrupt(Thread t);
}

@TargetClass(className = "jdk.internal.misc.PreviewFeatures", onlyWith = JDK19OrLater.class)
final class Target_jdk_internal_misc_PreviewFeatures {
@Alias
static native boolean isEnabled();

@Alias
static native void ensureEnabled();
}