Question

My applet is getting unexpectedly terminated. From log, I could see

JVM heartbeat .. dead, send ts: 654648165466, now ts: 654658163729, dT 9998263

I had a shutdown hook to see who is killing the applet & I got the following

stack Trace ………Thread[Java Plug-In Heartbeat Thread,5,main]

java.lang.Object.wait(Native Method)
java.lang.Thread.join(Unknown Source)
java.lang.Thread.join(Unknown Source)
java.lang.ApplicationShutdownHooks.runHooks(Unknown Source)
java.lang.ApplicationShutdownHooks$1.run(Unknown Source)
java.lang.Shutdown.runHooks(Unknown Source)
java.lang.Shutdown.sequence(Unknown Source)
java.lang.Shutdown.exit(Unknown Source)
java.lang.Runtime.exit(Unknown Source)
java.lang.System.exit(Unknown Source)
sun.plugin2.main.client.PluginMain.exit(Unknown Source)
sun.plugin2.main.client.PluginMain.access$1300(Unknown Source)
sun.plugin2.main.client.PluginMain$HeartbeatThread.run(Unknown Source)

I don’t understand why heartbeat Thread is working here. I don’t have multiple jvms & it is single applet without any socket communication. Only data transfer to server is through http

Answer 1

from the source code of PluginMain, it looks like we can prevent the HeartBeatThread from starting by setting an environment variable JPI_PLUGIN2_NO_HEARTBEAT to some value

http://www.javasourcecode.org/html/open-source/jdk/jdk-6u23/sun/plugin2/main/client/PluginMain.java.html