Memory leak when running Angular Universal

[ESchuderer]

Describe the bug SAP Spartacus memory consumption doesn't free up with a few continuous concurrent requests (10+ requests). This causes the node.js process to run out of memory and all SSR requests to time out.

Memory grows quickly even for simple operations like opening the homepage, indicating a memory leak.

Tell us the version of Spartacus

• Library version: 4.2.1 & 4.3.8

To Reproduce Steps to reproduce the behavior:

1. Setup a new spartacus storefront with Angular 12 and Spartacus 4.3.x
2. Setup SSR
3. Run load tests against the fresh Spartacus installation

Expected behavior Memory consumption stays low

Screenshots

Additional context Setting the cacheSize configuration according to https://sap.github.io/spartacus-docs/server-side-rendering-optimization/#configuring-the-ssr-optimization-engine helps to mitigate the issue, preventing OOM errors.

But SSR will still time out and redirect to CSR while impacting performance.

Setting the property inlineCriticalCss introduced by Angular 12 didn't mitigate the issue:

server.engine(
    'html',
    ngExpressEngine({
      bootstrap: AppServerModule,
      inlineCriticalCss: false
    }),
  );

[ESchuderer]

Useful linting tools to prevent such issues: https://github.com/cartant/eslint-plugin-rxjs https://github.com/cartant/eslint-plugin-rxjs-angular

Useful operator to unsubscribe on destroy: https://github.com/ngneat/until-destroy

[ESchuderer]

Potential leak in PageLayoutComponent as the Subject is not completed

Solution, call complete (not unsubscribe!) during destruction

ngOnDestroy(): void {
    this.section$.complete();
  }

[ESchuderer]

Observable profiler to check mem leaks: https://github.com/awerlang/observable-profiler

[ESchuderer]