Memory consumption issue

[Tirloni, Giovanni]

Hello,

 While running load tests on the preferences server (for benchmark and
 capacity planning purposes), the memory consumption of the node
 processes started to climb very quickly. To work around it and keep the
 tests going, we were restarting the processes when they reached
 100-200MB (which coincided with CPU usage nearing 85-95%). At some
 point the monitoring script was restarting processes every 10 seconds
 and it did not seem worth it anymore. This was done using the latest
 code from gpii/universal (2015-07-01), the dependencies specified in
 the package.json file and node 0.10.36.

 I deployed the same code on my desktop, primed the CouchDB database
 with the testData and tried to reproduce the issue with a simple test
 (curl http://localhost:8081/preferences/elaine). I ran a few tests,
 varying the wait time between the requests to increase the pressure, as
 shown below. You can see in the graph a few 30-second plateaus between
 tests. I then left the preferences server sitting idle for 6 minutes,
 and the memory usage stayed flat at around 700MB, there were no
 connections active at that time. The attached file contains the CSV
 data (in KB) and the generated chart. 

19:55:30 - 19:56:30 - wait 500ms
19:57:00 - 19:58:00 - wait 250ms
19:58:30 - 19:59:30 - wait 100ms
20:00:00 - 20:01:00 - wait  50ms
20:01:30 - 20:02:30 - wait  25ms
20:03:00 - 20:05:00 - wait  10ms
20:05:00 - 20:11:00 - no activity

 I tried my hand at tracing/profiling the code but unfortunately I'm
 closer to a JS newbie than an expert and I couldn't discover anything
 Earth shattering. I did notice the number of  array/string/closure
 objects accounted for most of the memory used. I also collected heap
 snapshots using the 'heapdump' library (three samples available here:
 http://1drv.ms/1f6Rmfp)

Regards,
Giovanni
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