Memory leak

[scottschafer]

I don't know if this is at all an issue with react2angular, but I am experiencing some nasty leaks with a React component wrapped with react2angular. I have a workaround listed at the end, but it's ugly and I'd like to find a better solution.

My component looks like this:

export class EncounterView extends React.Component {
  memLeak = new Int8Array(100000000);
  componentWillUnmount() {
    debugger;
  }
  render() {
    return <h1>no-op</h1>;
  }
}

// Register component for AngularJS integration
module('talixCodingInsight')
  .component(
    'encounterView',
    react2angular(
      EncounterView
    )
  );

Then this component is embedded into my AngularJS app like this, hooked up with $stateProvider.state:

    <encounter-view></encounter-view>`,

The problem here is that when I go to this route and leave it, componentWillUnmount() is called but the buffer is not released.

Here are the retainers:

memLeak in EncounterView@711833 | 11 | 1360 % | 100 001 32852 %
stateNode in FiberNode@708915 | 10 | 2880 % | 100 001 61652 %
lastEffect in FiberNode@707329 | 9 | 2880 % | 100 007 13652 %
currentFiber in system / Context@90437 | 8 | 11 6080 % | 100 539 41652 %
context in overrideHookState()@68727 | 7 | 640 % | 1680 %

However, I did find a workaround. Which is nasty. The fix was to use ng-if to remove the component when changing the route. If I do that, then the buffer is released.

I don't like this solution though. Any ideas as to what's happening?

[liquidprogrammer]

Hi @scottschafer! Im facing the same issue, can u please provide an example of ur hacky ng-if fix? I tried do that ng-if hack somewhere on the top level of routing, but memory was still leaked (but less than without that). Just wanted to double check where in the app u apply that trick so it helps to avoid leaks

[brianunlam]

@scottschafer how did you do to get the leaks that way?

memLeak in EncounterView@711833 | 11 | 1360 % | 100 001 32852 % stateNode in FiberNode@708915 | 10 | 2880 % | 100 001 61652 % lastEffect in FiberNode@707329 | 9 | 2880 % | 100 007 13652 % currentFiber in system / Context@90437 | 8 | 11 6080 % | 100 539 41652 % context in overrideHookState()@68727 | 7 | 640 % | 1680 %

[scottschafer]

To @liquidprogrammer , the fix looked something like this in the template:

      <encounter-view
        id="encounter-view-ng"
        ng-if="$ctrl.includeEncounterView"

Where EncounterView is the react2angular component.

Then when changing states away from this route, I set includeEncounterView to false and wait until the view is torn down before proceeding to the route.

      $scope.$on('$stateChangeStart', (event, toState, toParams, fromState, fromParams) => {
        if (toState.name !== 'home.patients.details.coding.encounter') {
          this.includeEncounterView = false;
          if ($('#encounter-view-ng').length) {
            event.preventDefault();

            const checkTornDownInterval = $interval(() => {
              if (!$('#encounter-view-ng').length) {
                $interval.cancel(checkTornDownInterval);
                $state.go(toState, toParams);
              }
            }, 0);
          }
        }

@brianunlam, It's been a while since I looked at this. SInce I reported this bug, I discovered that React seems to hang onto references and free them periodically. This means that you might need to take a memory snapshot, perform an operation that shouldn't leak and then WAIT before taking another snapshot - if you do this too quickly, you might see leaks that don't really exist.

But in this case, it did seem like the memory was steadily increasing. I don't know, this leak/non-leak was driving me a little bit crazy. Now I have code that I'm afraid to touch. ;)

I asked about React hanging onto references here BTW: https://stackoverflow.com/questions/58984601/reactdom-seems-to-be-caching-and-releasing-elements-so-is-this-a-leak

Thanks for a great and useful library. I don't think it's the culprit here.

[liquidprogrammer]

@scottschafer hi, thanks! I'll try that out. I didn't try to ng-if the component itself, i only tried to add ng-if at the top level root component, but that helped only a bit.