Question

I managed to generate thread dump when my test case hanging. However, it doesn’t seemed to be a deadlock, a race condition or resource contention. But it definitedly hung while running the test case in my loading testing tool with 3 virtual users. Anyone can point me to the right direction here? Cheers

"Servlet.Engine.Transports : 387" daemon prio=5 tid=0x15386f8 nid=0x943 waiting on monitor [0xb4781000..0xb4781a00]
    at java.lang.Object.wait(Native Method)
    at java.lang.Object.wait(Object.java:415)
    at com.ibm.ws.util.BoundedBuffer.take(BoundedBuffer.java:161)
    at com.ibm.ws.util.ThreadPool.getTask(ThreadPool.java:422)
    at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:669)

"Servlet.Engine.Transports : 385" daemon prio=5 tid=0x51e898 nid=0x93e waiting on monitor [0xb3281000..0xb3281a00]
    at java.lang.Object.wait(Native Method)
    at java.lang.Object.wait(Object.java:415)
    at com.ibm.ws.util.BoundedBuffer.take(BoundedBuffer.java:161)
    at com.ibm.ws.util.ThreadPool.getTask(ThreadPool.java:422)
    at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:669)

"Servlet.Engine.Transports : 384" daemon prio=5 tid=0x464760 nid=0x93d waiting on monitor [0xb3381000..0xb3381a00]
    at java.lang.Object.wait(Native Method)
    at java.lang.Object.wait(Object.java:415)
    at com.ibm.ws.util.BoundedBuffer.take(BoundedBuffer.java:161)
    at com.ibm.ws.util.ThreadPool.getTask(ThreadPool.java:422)
    at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:669)

"Servlet.Engine.Transports : 382" daemon prio=5 tid=0x1141de8 nid=0x8a0 waiting on monitor [0xb3581000..0xb3581a00]
    at java.lang.Object.wait(Native Method)
    at java.lang.Object.wait(Object.java:415)
    at com.ibm.ws.util.BoundedBuffer.take(BoundedBuffer.java:161)
    at com.ibm.ws.util.ThreadPool.getTask(ThreadPool.java:422)
    at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:669)

"Servlet.Engine.Transports : 380" daemon prio=5 tid=0x1151ad8 nid=0x6b5 waiting on monitor [0xb3e81000..0xb3e81a00]
    at java.lang.Object.wait(Native Method)
    at java.lang.Object.wait(Object.java:415)
    at com.ibm.ws.util.BoundedBuffer.take(BoundedBuffer.java:161)
    at com.ibm.ws.util.ThreadPool.getTask(ThreadPool.java:422)
    at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:669)

"Servlet.Engine.Transports : 366" daemon prio=5 tid=0x1a1d110 nid=0x3fb waiting on monitor [0xb4b81000..0xb4b81a00]
    at java.lang.Object.wait(Native Method)
    at java.lang.Object.wait(Object.java:415)
    at com.ibm.ws.util.BoundedBuffer.take(BoundedBuffer.java:161)
    at com.ibm.ws.util.ThreadPool.getTask(ThreadPool.java:422)
    at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:669)

"Servlet.Engine.Transports : 365" daemon prio=5 tid=0x4e8bd8 nid=0x3fa waiting on monitor [0xb6281000..0xb6281a00]
    at java.lang.Object.wait(Native Method)
    at java.lang.Object.wait(Object.java:415)
    at com.ibm.ws.util.BoundedBuffer.take(BoundedBuffer.java:161)
    at com.ibm.ws.util.ThreadPool.getTask(ThreadPool.java:422)
    at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:669)

"Servlet.Engine.Transports : 362" daemon prio=5 tid=0x17055b0 nid=0x3f7 waiting on monitor [0xb3481000..0xb3481a00]
    at java.lang.Object.wait(Native Method)
    at java.lang.Object.wait(Object.java:415)
    at com.ibm.ws.util.BoundedBuffer.take(BoundedBuffer.java:161)
    at com.ibm.ws.util.ThreadPool.getTask(ThreadPool.java:422)
    at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:669)

"Servlet.Engine.Transports : 356" daemon prio=5 tid=0x1ddbae0 nid=0x3f1 waiting on monitor [0xb9c01000..0xb9c01a00]
    at java.lang.Object.wait(Native Method)
    at java.lang.Object.wait(Object.java:415)
    at com.ibm.ws.util.BoundedBuffer.take(BoundedBuffer.java:161)
    at com.ibm.ws.util.ThreadPool.getTask(ThreadPool.java:422)
    at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:669)

"Servlet.Engine.Transports : 299" daemon prio=5 tid=0x2519028 nid=0x3b5 waiting on monitor [0xb6001000..0xb6001a00]
    at java.lang.Object.wait(Native Method)
    at java.lang.Object.wait(Object.java:415)
    at com.ibm.ws.util.BoundedBuffer.take(BoundedBuffer.java:161)
    at com.ibm.ws.util.ThreadPool.getTask(ThreadPool.java:422)
    at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:669)

Answer 1

Unless you have your own com.ibm.* class running, it looks like all these threads are normal “I’m waiting for something to do” threads of an application server. Are you sure this is the full thread dump? It appears that your test has probably executed and finished and the container is waiting for something to do…?