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Threads

The Threads page (Administration > System Status > Threads) shows all processor threads running inside the Mango JVM. This is a critical diagnostic tool for identifying performance bottlenecks, deadlocks, and runaway tasks.

Viewing Threads​

The threads table displays every active thread along with sortable columns for:

ColumnDescription
NameThe thread name, which typically identifies its purpose (e.g., Polling-DataSource-1, medium-priority-pool-thread-3)
CPU TimeTotal CPU time consumed by the thread since it was created
User TimeCPU time spent in user-mode code (excludes kernel time)
StateCurrent thread state: RUNNABLE, WAITING, TIMED_WAITING, or BLOCKED

The Threads page showing the sortable table of running threads with Name, CPU Time, User Time, and State columns

Viewing Stack Traces​

Click any row in the threads table to view the Stack Trace for that thread. The stack trace shows the exact call chain the thread is executing, from the current method down to the thread entry point. This is invaluable for diagnosing:

  • Blocked threads -- If a thread is in BLOCKED state, the stack trace shows which lock it is waiting to acquire and which thread holds that lock.
  • Long-running operations -- A thread stuck in the same method across multiple refreshes may indicate an infinite loop, a slow database query, or a network timeout.
  • Deadlocks -- Two or more threads each waiting for a lock held by the other.

A thread stack trace popup showing the method call chain for a selected thread

Common Mango Threads​

Understanding what each thread does helps you interpret the thread list:

Thread Name PatternPurpose
high-priority-pool-thread-*Executes data source polling, event detection, and batch writes
medium-priority-pool-thread-*Handles backups, audit events, and data point notifications
low-priority-pool-thread-*Processes emails, reports, and alarm notifications
Polling-DataSource-*Scheduled polling timers for individual data sources
NoSQL-BatchWrite-*Background threads writing point values to the NoSQL store
WebSocket-*Manages real-time UI updates via WebSocket connections
http-*Jetty HTTP server threads handling web requests

Downloading Thread Dumps​

Click the Download Thread Dump button to export the entire thread dump as a JSON file. This is useful for:

  • Sharing with Radix IoT support for diagnosis.
  • Comparing thread states over time to identify trends.
  • Archiving thread snapshots during performance investigations.

For more detailed JVM diagnostics on Linux, including jstack and flight recordings, see Linux Diagnostic Information.

Diagnosing Thread Issues​

High CPU Usage​

Sort threads by CPU Time to identify the most active threads. If a single thread is consuming far more CPU than others, examine its stack trace to understand what operation it is performing. Common causes include complex scripting data points, aggressive polling rates, or large report generation.

Thread Pool Exhaustion​

If the high-priority pool is fully utilized, new tasks will be rejected. You can monitor this on the Work Items page. Increase the pool size in System Settings if necessary, but also investigate why tasks are accumulating -- the root cause may be slow data source responses, disk I/O bottlenecks, or misconfigured polling rates.

Waiting Threads​

A large number of threads in WAITING or TIMED_WAITING state is normal -- these are idle threads in pools waiting for work. However, threads in BLOCKED state indicate contention that may degrade performance.