How to monitor the memory usage of Node js

Question

How can I monitor the memory usage of Node js

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On Linux Unix  note  Mac OS is a Unix  use top and press M  Shift M  to sort processes by memory usage   On Windows use the Task Manager

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Also  if you d like to know global memory rather than node process    var os   require  os     os freemem    os totalmem      See documentation

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The original memwatch is essentially dead  Try memwatch-next instead  which seems to be working well on modern versions of Node

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The built-in process module has a method memoryUsage that offers insight in the memory usage of the current Node js process  Here is an example from in Node v0 12 2 on a 64-bit system     node --expose-gc  gt  process memoryUsage        Initial usage   rss  19853312  heapTotal  9751808  heapUsed  4535648    gt  gc                         Force a GC for the baseline  undefined  gt  process memoryUsage        Baseline memory usage    rss  22269952  heapTotal  11803648  heapUsed  4530208    gt  var a   new Array 1e7      Allocate memory for 10m items in an array undefined  gt  process memoryUsage        Memory after allocating so many items   rss  102535168  heapTotal  91823104  heapUsed  85246576    gt  a   null                   Allow the array to be garbage-collected null  gt  gc                         Force GC  requires node --expose-gc  undefined  gt  process memoryUsage        Memory usage after GC   rss  23293952  heapTotal  11803648  heapUsed  4528072    gt  process memoryUsage        Memory usage after idling   rss  23293952  heapTotal  11803648  heapUsed  4753376     In this simple example  you can see that allocating an array of 10M elements consumers approximately 80MB  take a look at heapUsed   If you look at V8 s source code  Array  New  Heap  AllocateRawFixedArray  FixedArray  SizeFor   then you ll see that the memory used by an array is a fixed value plus the length multiplied by the size of a pointer  The latter is 8 bytes on a 64-bit system  which confirms that observed memory difference of 8 x 10   80MB makes sense

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node-memwatch   detect and find memory leaks in Node JS code   Check this tutorial Tracking Down Memory Leaks in Node js

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You can use node js memoryUsage const formatMemoryUsage    data    gt     Math round data   1024   1024   100    100  MB   const memoryData   process memoryUsage    const memoryUsage                     rss     formatMemoryUsage memoryData rss   - gt  Resident Set Size - total memory allocated for the process execution                   heapTotal     formatMemoryUsage memoryData heapTotal   - gt  total size of the allocated heap                   heapUsed     formatMemoryUsage memoryData heapUsed   - gt  actual memory used during the execution                   external     formatMemoryUsage memoryData external   - gt  V8 external memory      console log memoryUsage            quot rss quot    quot 177 54 MB - gt  Resident Set Size - total memory allocated for the process execution quot        quot heapTotal quot    quot 102 3 MB - gt  total size of the allocated heap quot        quot heapUsed quot    quot 94 3 MB - gt  actual memory used during the execution quot        quot external quot    quot 3 03 MB - gt  V8 external memory quot

[javascript] How to monitor the memory usage of Node.js?

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