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https://issues.apache.org/jira/browse/METRON-1790?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16645111#comment-16645111
 ] 

ASF GitHub Bot commented on METRON-1790:
----------------------------------------

Github user nickwallen commented on a diff in the pull request:

    https://github.com/apache/metron/pull/1208#discussion_r224114432
  
    --- Diff: 
metron-interface/metron-alerts/src/app/pcap/pcap-panel/pcap-panel.component.ts 
---
    @@ -35,40 +35,40 @@ export class PcapPanelComponent implements OnInit, 
OnDestroy {
       pdml: Pdml = null;
       pcapRequest: PcapRequest;
       resetPaginationForSearch: boolean;
    -
    -  statusSubscription: Subscription;
    -  cancelSubscription: Subscription;
    -  submitSubscription: Subscription;
    -  getSubscription: Subscription;
       queryRunning = false;
       queryId: string;
       progressWidth = 0;
       pagination: PcapPagination = new PcapPagination();
       savedPcapRequest: {};
       errorMsg: string;
       cancelConfirmMessage = 'Are you sure want to cancel the running query?';
    +  subscriptions: {
    +    [key: string]: Subscription
    +  } = {};
     
       constructor(private pcapService: PcapService) { }
     
       ngOnInit() {
         this.pcapRequest = new PcapRequest();
    -    this.pcapService.getRunningJob().subscribe((statusResponses: 
PcapStatusResponse[]) => {
    +    this.subscriptions['runningJobSubscription'] = 
this.pcapService.getRunningJob().subscribe((statusResponses: 
PcapStatusResponse[]) => {
    --- End diff --
    
    Why do we never see an unsubscribe for 'runningJobSubscription'?


> Unsubscribe from every observable in the pcap panel UI component
> ----------------------------------------------------------------
>
>                 Key: METRON-1790
>                 URL: https://issues.apache.org/jira/browse/METRON-1790
>             Project: Metron
>          Issue Type: Improvement
>            Reporter: Tamas Fodor
>            Assignee: Tamas Fodor
>            Priority: Minor
>
> 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]
> This is the place to free resources that won't be garbage collected 
> automatically. Unsubscribe from Observables and DOM events. Stop interval 
> timers.



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