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From "Tamas Fodor (JIRA)" <j...@apache.org>
Subject [jira] [Created] (METRON-1767) Unsubscribe from every observable in the pcap panel UI component
Date Wed, 05 Sep 2018 09:43:00 GMT
Tamas Fodor created METRON-1767:
-----------------------------------

             Summary: Unsubscribe from every observable in the pcap panel UI component
                 Key: METRON-1767
                 URL: https://issues.apache.org/jira/browse/METRON-1767
             Project: Metron
          Issue Type: Improvement
            Reporter: Tamas Fodor
            Assignee: Tamas Fodor


There are a lot of http requests performed in the pcap panel ui component and we just unsubscribe
from some of them when the component is no longer rendered on the screen. It could cause memory
consumption issues. Because of the active subscriptions, the garbage collector is not able
to remove these objects from the memory, however they're not needed to be there anymore.

There's another benefit of unsubscribing from these http calls. If the user leaves the pcap
tab but there are pending requests, the unsubscribe method cancels the active xhrs immediately
so it won't wait for fulfilment unnecessarily. 

[https://github.com/apache/metron/blob/master/metron-interface/metron-alerts/src/app/pcap/pcap-panel/pcap-panel.component.ts#L54]

I would also refactor that part when we convert an observable to a promise. I would keep it
as an observable. By doing this, we would be able to unsubscribe from it as well in the destructor
method. Promises are not cancelable. 

[https://github.com/apache/metron/blob/master/metron-interface/metron-alerts/src/app/pcap/pcap-panel/pcap-panel.component.ts#L70]

 

Resources:

[https://angular.io/guide/lifecycle-hooks#ondestroy]
{quote}This is the place to free resources that won't be garbage collected automatically.
Unsubscribe from Observables and DOM events. Stop interval timers. Unregister all callbacks
that this directive registered with global or application services. You risk memory leaks
if you neglect to do so.
{quote}



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