Created
December 11, 2020 01:26
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Change MaxJavaStackTraceDepth JVM flag in runtime
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import sun.jvm.hotspot.debugger.Address; | |
import sun.jvm.hotspot.runtime.VM; | |
import sun.jvm.hotspot.tools.Tool; | |
import java.io.IOException; | |
import java.io.RandomAccessFile; | |
/** | |
* Changes -XX:MaxJavaStackTraceDepth flag to 1000000 in runtime | |
* without restarting the JVM. | |
* See https://stackoverflow.com/q/65239783/3448419 | |
* | |
* How to run on JDK 8: | |
* java -cp .:$JAVA_HOME/lib/sa-jdi.jar ChangeVMFlag <pid> | |
* | |
* On Java 9+: | |
* java --add-modules=jdk.hotspot.agent \ | |
* --add-exports jdk.hotspot.agent/sun.jvm.hotspot.tools=ALL-UNNAMED \ | |
* --add-exports jdk.hotspot.agent/sun.jvm.hotspot.runtime=ALL-UNNAMED \ | |
* --add-exports jdk.hotspot.agent/sun.jvm.hotspot.debugger=ALL-UNNAMED \ | |
* ChangeVMFlag <pid> | |
*/ | |
public class ChangeVMFlag extends Tool { | |
private static String pid; | |
@Override | |
public void run() { | |
Address addr = VM.getVM().getCommandLineFlag("MaxJavaStackTraceDepth").getAddress(); | |
long addrValue = VM.getVM().getDebugger().getAddressValue(addr); | |
try (RandomAccessFile raf = new RandomAccessFile("/proc/" + pid + "/mem", "rw")) { | |
raf.seek(addrValue); | |
raf.writeInt(Integer.reverseBytes(1_000_000)); | |
} catch (IOException e) { | |
e.printStackTrace(); | |
} | |
} | |
public static void main(String[] args) { | |
pid = args[0]; | |
new ChangeVMFlag().execute(new String[]{pid}); | |
} | |
} |
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