Reduce memory footprint

[appurva21]

Context / Issue:

bridge.js receives the options object as an argument with bootCode supplied by the consumer.

Inside bridge.js, worker is spawned and multiple event/timers are setup. bootCode string is only required to spawn the worker and should get garbage collected post that. But right now, while adding event listeners and callbacks for timers, options object is referenced, which prevents GC of options.bootCode.

Fix:

Destructure options and directly use the values wherever required to prevent unintended references to the complete object.

Benchmark:

script:

const UniversalVM = require('uvm');

UniversalVM.spawn({
    bootCode: `
        bridge.on('loopback', function (data) {
            bridge.dispatch('loopback', data);
        });
       /* INSERT 10MB string here */
    `
}, (_, context) => {
    context.on('loopback', function () {
       context.disconnect();
    });

    context.dispatch('loopback');
});

Baseline (develop, empty bootCode): 3.8MB

Before Fix (develop, 10.5MB bootCode): 24.7MB (3.8 + ~2*10.5)

Note

• options.bootCode persisted (second string in the right panel)
• the script has significant memory footprint as well due to the presence of large string in it, thus 2*10.5
  

After fix (current, 10.5MB bootCode): 14.2MB (3.8 + 10.5)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (cc7fda1) to head (a042d2d).
Report is 1 commits behind head on feature/refactor-worker-interface.

Additional details and impacted files

@@                         Coverage Diff                         @@
##           feature/refactor-worker-interface      #711   +/-   ##
===================================================================
  Coverage                             100.00%   100.00%           
===================================================================
  Files                                      5         5           
  Lines                                    108       109    +1     
  Branches                                  10        10           
===================================================================
+ Hits                                     108       109    +1     

Flag	Coverage Δ
unit	100.00% <100.00%> (ø)

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