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A Lumino or Robin controller can also be used to connect to a server via a direct admin connection over TCP to listen for heartbeats for monitoring purposes. The XVMs stats thread will queue copies of each emitted heartbeats to each connected admin client. 

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Heartbeat Output

When heartbeat tracing is enabled heartbeat trace is emitted to the nv.server.heartbeat logger at a level of info. This section discussed the output format of heartbeats. 

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[System Stats]
TueSat JunMay 2813 1712:2614:03 PDT 20162017 'ems1market' server (pid=5036054449) 2 apps (collection time=739828390 ns)
System: 20 processors, load average: 20.30
Memory: HEAP 8.0G init 6.6G used 7.8G commit 7.8G73 (load 0.10 process, 0.10 total system)
Memory (system): 94.4G total, 89.8G free, 5.5G committed (Swap: 96.6G total, 96.6G free)
Memory (proc): HEAP 1.5G init, 522M used, 1.5G commit, 1.5G max NON-HEAP 2M init, 44M47M used, 46M48M commit, 0K max
Threads: 26Disk:
  [/ Total: 49.2GB, Usable:  18GB, Free:  18GB]
  [/dev/shm Total: 47.2GB, Usable: 47.2GB, Free: 47.2GB]
  [/boot Total: 484.2MB, Usable: 422.4MB, Free: 422.4MB]
  [/home Total: 405.2GB, Usable: 267GB, Free: 267GB]
  [/distributions Total: 196.9GB, Usable: 8.1GB, Free: 8.1GB]
Threads: 20 total (2316 daemon) 2721 peak
JIT: HotSpot 64-Bit Tiered Compilers, time: 119972959 ms
[6 6404 GC:
...ParNew [0 collections, commulative time: 0 ms]
...MarkSweepCompact [21 8771 collections, commulative time: 54 ms]

The above trace can be interpreted as follows:

General Info

• Date and time that statistics gathering started
• Server name
• Server PID
• Number of apps running in the server
• Time spent gathering server statistics (for the current interval, excluding formatting)

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• Number of available processors
• System load average

Memory Info

For the entire system:

• Total available memory
• The free memory
• Commit memory
• Swap total/free 

For the process:

• Initial heap size
• Heap used
• Heap committed
• Max heap size
• Initial non-heap size
• Non-heap memory used
• Non-heap memory committed
• Non-heap memory max size

 JDK 7 or newer is needed to collect all available memory stats. In addition some stats are not available on all jvms. 

Disk

For each volume available:

• Total space
• Usable space
• Available space.

 Listing of disk system roots required JDK7+, with JDK 6 or below, some disk information may not be available. 

Thread Info

• Total thread count
• Daemon thread count
• Peak thread count

JIT Info

• JIT name

• Total compilation time

GC Info

• Collection count (for all GCs)
• Collection time (for all GCs)

Thread Stats

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