From 265804a750bcb27e487cf285e3b1527955cd0efd Mon Sep 17 00:00:00 2001
From: zzz <zzz@i2pmail.org>
Date: Mon, 6 Jun 2022 17:01:15 -0400
Subject: [PATCH] Console: Add deadlock detector
---
.../i2p/router/web/ConfigServiceHandler.java | 3 +
.../net/i2p/router/web/DeadlockDetector.java | 138 ++++++++++++++++++
.../i2p/router/web/RouterConsoleRunner.java | 1 +
3 files changed, 142 insertions(+)
create mode 100644 apps/routerconsole/java/src/net/i2p/router/web/DeadlockDetector.java
diff --git a/apps/routerconsole/java/src/net/i2p/router/web/ConfigServiceHandler.java b/apps/routerconsole/java/src/net/i2p/router/web/ConfigServiceHandler.java
index 71a2e410b9..3f06e0d545 100644
--- a/apps/routerconsole/java/src/net/i2p/router/web/ConfigServiceHandler.java
+++ b/apps/routerconsole/java/src/net/i2p/router/web/ConfigServiceHandler.java
@@ -277,6 +277,9 @@ public class ConfigServiceHandler extends FormHandler {
}
File wlog = wrapperLogFile(_context);
addFormNotice(_t("Threads dumped to {0}", wlog.getAbsolutePath()));
+ boolean deadlock = DeadlockDetector.detect(_context);
+ if (deadlock)
+ addFormErrorNoEscape("Deadlock detected!<br><a href=\"/logs\">Please report using the information on the logs page!</a><br>After reporting, please restart your router!");
} else if (_t("View console on startup").equals(_action)) {
browseOnStartup(true);
addFormNotice(_t("Console is to be shown on startup"));
diff --git a/apps/routerconsole/java/src/net/i2p/router/web/DeadlockDetector.java b/apps/routerconsole/java/src/net/i2p/router/web/DeadlockDetector.java
new file mode 100644
index 0000000000..c32678b867
--- /dev/null
+++ b/apps/routerconsole/java/src/net/i2p/router/web/DeadlockDetector.java
@@ -0,0 +1,138 @@
+package net.i2p.router.web;
+
+import java.lang.management.ManagementFactory;
+import java.lang.management.ThreadInfo;
+import java.lang.management.ThreadMXBean;
+
+import net.i2p.I2PAppContext;
+import net.i2p.util.Log;
+import net.i2p.util.SimpleTimer2;
+
+/**
+ * Periodic check
+ * ref: https://dzone.com/articles/how-detect-java-deadlocks
+ *
+ * In routerconsole because java.lang.management is
+ * not available in Android.
+ *
+ * @since 0.9.55
+ */
+class DeadlockDetector extends SimpleTimer2.TimedEvent {
+
+ private final I2PAppContext _context;
+ private final Log _log;
+ private static final String PROP_INTERVAL = "router.deadlockDetectIntervalHours";
+ private static final long DEFAULT_INTERVAL = 24;
+
+ public DeadlockDetector(I2PAppContext ctx) {
+ super(ctx.simpleTimer2());
+ _context = ctx;
+ _log = _context.logManager().getLog(DeadlockDetector.class);
+ long interval = getInterval();
+ if (interval > 0)
+ schedule(interval);
+ }
+
+ private long getInterval() {
+ long rv = _context.getProperty(PROP_INTERVAL, DEFAULT_INTERVAL);
+ return rv * 60*60*1000L;
+ }
+
+ public void timeReached() {
+ long start = System.currentTimeMillis();
+ boolean detected = detect();
+ if (!detected) {
+ long time = System.currentTimeMillis() - start;
+ if (_log.shouldDebug())
+ _log.debug("No deadlocks detected, took " + time + "ms");
+ long interval = getInterval();
+ if (interval > 0)
+ schedule(interval);
+ }
+ }
+
+ private boolean detect() {
+ return detect(_context);
+ }
+
+ public static boolean detect(I2PAppContext ctx) {
+ try {
+ ThreadMXBean mxb = ManagementFactory.getThreadMXBean();
+ long[] ids = mxb.findDeadlockedThreads();
+ if (ids == null)
+ return false;
+ ThreadInfo[] infos;
+ try {
+ // java 10
+ //infos = mxb.getThreadInfo(ids, true, true, Integer.MAX_VALUE);
+ // java 6
+ infos = mxb.getThreadInfo(ids, true, true);
+ } catch (UnsupportedOperationException e) {
+ // won't throw
+ infos = mxb.getThreadInfo(ids, Integer.MAX_VALUE);
+ }
+ StringBuilder buf = new StringBuilder(2048);
+ buf.append("Deadlock detected, please report\n\n");
+ for (int i = 0; i < infos.length; i++) {
+ ThreadInfo info = infos[i];
+ if (info == null)
+ continue;
+ buf.append("Thread ").append(i).append(':');
+ buf.append(info.toString());
+ StackTraceElement[] stes = info.getStackTrace();
+ buf.append(" Stack Trace:\n");
+ for (StackTraceElement ste : stes) {
+ buf.append(" at ").append(ste.toString()).append('\n');
+ }
+ buf.append('\n');
+ }
+ buf.append("\nAfter reporting, please restart your router!\n");
+ Log log = ctx.logManager().getLog(DeadlockDetector.class);
+ log.log(Log.CRIT, buf.toString());
+ } catch (Throwable t) {
+ // class not found, unsupportedoperation, ...
+ Log log = ctx.logManager().getLog(DeadlockDetector.class);
+ log.warn("fail", t);
+ return false;
+ }
+ return true;
+ }
+
+/*
+ public static void main(String[] args) {
+ final Object o1 = new Object();
+ final Object o2 = new Object();
+ Thread t1 = new Thread(new Runnable() {
+ public void run() {
+ synchronized(o1) {
+ try { Thread.sleep(1000); } catch (InterruptedException ie) {}
+ // should hang here
+ synchronized(o2) {
+ System.out.println("Test fail");
+ }
+ }
+ }
+ });
+ t1.start();
+ Thread t2 = new Thread(new Runnable() {
+ public void run() {
+ synchronized(o2) {
+ // should hang here
+ synchronized(o1) {
+ System.out.println("Test fail");
+ }
+ }
+ }
+ });
+ t2.start();
+ try { Thread.sleep(1000); } catch (InterruptedException ie) {}
+ long start = System.currentTimeMillis();
+ boolean yes = detect(I2PAppContext.getGlobalContext());
+ if (!yes)
+ System.out.println("Test fail");
+ long time = System.currentTimeMillis() - start;
+ System.out.println("Test took " + time + "ms");
+ }
+*/
+}
+
diff --git a/apps/routerconsole/java/src/net/i2p/router/web/RouterConsoleRunner.java b/apps/routerconsole/java/src/net/i2p/router/web/RouterConsoleRunner.java
index 821cf0776d..eddae60e20 100644
--- a/apps/routerconsole/java/src/net/i2p/router/web/RouterConsoleRunner.java
+++ b/apps/routerconsole/java/src/net/i2p/router/web/RouterConsoleRunner.java
@@ -233,6 +233,7 @@ public class RouterConsoleRunner implements RouterApp {
checkJavaVersion();
startTrayApp();
startConsole();
+ new DeadlockDetector(_context);
}
/** @since 0.9.4 */
--
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