(The difference from WAITING is that the maximum waiting time is specified by the method parameter, and WAITING can be relieved by time as well as external changes.)ĭaemon threads stop working when there are no other non-daemon threads. TIMED_WAITING: The thread is waiting by using a sleep, wait, join or park method.WAITING: The thread is waiting by using a wait, join or park method.BLOCKED: The thread is waiting for a different thread to release its lock in order to get the monitor lock.(It may be in WAITING status due to the OS’s resource distribution.) RUNNABLE: The thread is occupying the CPU and processing a task.NEW: The thread is created but has not been processed yet.In order to analyze a thread dump, you need to know the status of threads. For a thread to own a monitor that is owned by a different thread, it needs to wait in the wait queue until the other thread releases its monitor. The monitor can be owned by only one thread. Thread synchronization on Java can be done using monitor. In order to ensure compatibility when multiple threads are trying to use shared resources, one thread at a time should be allowed to access the shared resources by using thread synchronization. Background Information for Java Threads Thread SynchronizationĪ thread can be processed with other threads at the same time. A thread dump will give you the information on the exact status of each thread. To analyze such issues, you need to use the thread dump. For example, to record a log, the thread trying to record the log must obtain a lock and access the shared resources.ĭeadlock is a special type of thread contention, in which two or more threads are waiting for the other threads to complete their tasks in order to complete their own tasks.ĭifferent issues can arise from thread contention. Different threads frequently access shared resources on a web application. Thread contention is a status in which one thread is waiting for a lock, held by another thread, to be lifted. If two or more threads utilize the same resources, a contention between the threads is inevitable, and sometimes deadlock occurs and this is one of the main situation where we need to take the thread dump for finding the root cause. A web server uses tens to hundreds of threads to process a large number of concurrent users.

Jprofiler run in separate thread