8000 Use jvmstat for JDKs 9+ programmatically (#8641) · DataDog/dd-trace-java@690dd95 · GitHub
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MattAlpamarziali
MattAlp
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amarziali
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Use jvmstat for JDKs 9+ programmatically (#8641)
1 parent b838ed1 commit 690dd95

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‎dd-java-agent/agent-bootstrap/src/main/java/datadog/trace/bootstrap/Agent.java

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Original file line numberDiff line numberDiff line change
@@ -3,6 +3,7 @@
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import static datadog.trace.api.ConfigDefaults.DEFAULT_STARTUP_LOGS_ENABLED;
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import static datadog.trace.api.Platform.isJavaVersionAtLeast;
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import static datadog.trace.api.Platform.isOracleJDK8;
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import static datadog.trace.api.telemetry.LogCollector.SEND_TELEMETRY;
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import static datadog.trace.bootstrap.Library.WILDFLY;
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import static datadog.trace.bootstrap.Library.detectLibraries;
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import static datadog.trace.util.AgentThreadFactory.AgentThread.JMX_STARTUP;
@@ -44,6 +45,7 @@
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import datadog.trace.util.AgentTaskScheduler;
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import datadog.trace.util.AgentThreadFactory.AgentThread;
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import datadog.trace.util.throwable.FatalAgentMisconfigurationError;
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import de.thetaphi.forbiddenapis.SuppressForbidden;
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import java.lang.instrument.Instrumentation;
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import java.lang.reflect.InvocationTargetException;
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import java.lang.reflect.Method;
@@ -291,6 +293,8 @@ public static void start(
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codeOriginEnabled = isFeatureEnabled(AgentFeature.CODE_ORIGIN);
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agentlessLogSubmissionEnabled = isFeatureEnabled(AgentFeature.AGENTLESS_LOG_SUBMISSION);
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patchJPSAccess(inst);
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if (profilingEnabled) {
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if (!isOracleJDK8()) {
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// Profiling agent startup code is written in a way to allow `startProfilingAgent` be called
@@ -420,6 +424,23 @@ private static void injectAgentArgsConfig(String agentArgs) {
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}
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}
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@SuppressForbidden
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public static void patchJPSAccess(Instrumentation inst) {
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if (Platform.isJavaVersionAtLeast(9)) {
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// Unclear if supported for J9, may need to revisit
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try {
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Class.forName("datadog.trace.util.JPMSJPSAccess")
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.getMethod("patchModuleAccess", Instrumentation.class)
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.invoke(null, inst);
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} catch (Exception e) {
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log.debug(
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SEND_TELEMETRY,
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"Failed to patch module access for jvmstat and Java version "
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+ Platform.getRuntimeVersion());
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}
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}
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}
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public static void shutdown(final boolean sync) {
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StaticEventLogger.end("Agent");
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StaticEventLogger.stop();

‎internal-api/build.gradle

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@@ -175,6 +175,7 @@ excludedClassesCoverage += [
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"datadog.trace.util.ComparableVersion.LongItem",
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"datadog.trace.util.ComparableVersion.StringItem",
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"datadog.trace.util.ConcurrentEnumMap",
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"datadog.trace.util.JPSUtils",
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"datadog.trace.util.MethodHandles",
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"datadog.trace.util.PidHelper",
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"datadog.trace.util.PidHelper.Fallback",

‎internal-api/internal-api-9/src/main/java/datadog/trace/util/JPMSJPSAccess.java

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@@ -0,0 +1,26 @@
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package datadog.trace.util;
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import java.lang.instrument.Instrumentation;
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import java.util.Collections;
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import java.util.Map;
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import java.util.Set;
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public class JPMSJPSAccess {
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public static void patchModuleAccess(Instrumentation inst) {
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Module unnamedModule = ClassLoader.getSystemClassLoader().getUnnamedModule();
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Module jvmstatModule = ModuleLayer.boot().findModule("jdk.internal.jvmstat").orElse(null);
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if (jvmstatModule != null) {
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Map<String, Set<Module>> extraOpens = Map.of("sun.jvmstat.monitor", Set.of(unnamedModule));
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// Redefine the module
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inst.redefineModule(
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jvmstatModule,
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Collections.emptySet(),
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extraOpens,
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extraOpens,
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Collections.emptySet(),
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Collections.emptyMap());
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}
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}
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}

‎internal-api/internal-api-9/src/test/groovy/datadog/trace/util/PidHelperTest.groovy

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@@ -1,11 +1,21 @@
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package datadog.trace.util
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import datadog.trace.test.util.DDSpecification
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import net.bytebuddy.agent.ByteBuddyAgent
45

56
class PidHelperTest extends DDSpecification {
67

78
def "PID is available everywhere we test"() {
89
expect:
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!PidHelper.getPid().isEmpty()
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}
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def "JPS via jvmstat is used when possible"() {
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when:
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def inst = ByteBuddyAgent.install()
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JPMSJPSAccess.patchModuleAccess(inst)
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then:
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JPSUtils.VMPids != null
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}
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}

‎internal-api/src/main/java/datadog/trace/util/JPSUtils.java

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@@ -0,0 +1,25 @@
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package datadog.trace.util;
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3+
import de.thetaphi.forbiddenapis.SuppressForbidden;
4+
import java.lang.reflect.Method;
5+
import java.util.Set;
6+
import org.slf4j.Logger;
7+
import org.slf4j.LoggerFactory;
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9+
public final class JPSUtils {
10+
private static final Logger log = LoggerFactory.getLogger(JPSUtils.class);
11+
12+
@SuppressForbidden
13+
public static Set<String> getVMPids() {
14+
try {
15+
Class<?> monitoredHostClass = Class.forName("sun.jvmstat.monitor.MonitoredHost");
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Method getMonitoredHostMethod =
17+
monitoredHostClass.getDeclaredMethod("getMonitoredHost", String.class);
18+
Object vmHost = getMonitoredHostMethod.invoke(null, "localhost");
19+
return (Set<String>) monitoredHostClass.getDeclaredMethod("activeVms").invoke(vmHost);
20+
} catch (Exception e) {
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log.debug("Failed to invoke jvmstat with exception ", e);
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return null;
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}
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}
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}

‎internal-api/src/main/java/datadog/trace/util/PidHelper.java

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@@ -65,6 +65,11 @@ private static String findPid() {
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}
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public static Set<String> getJavaPids() {
68+
// Attempt to use jvmstat directly, fall through to jps process fork strategy
69+
Set<String> directlyObtainedPids = JPSUtils.getVMPids();
70+
if (directlyObtainedPids != null) {
71+
return directlyObtainedPids;
72+
}
6873
// there is no supported Java API to achieve this
6974
// one could use sun.jvmstat.monitor.MonitoredHost but it is an internal API and can go away at
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// any time -

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