perf: reduce js_run_devserver cycle event parsing memory usage

[jbedard]

Changes are visible to end-users: no

Test plan

• Covered by existing test cases
• Manual testing; please provide instructions so we can reproduce: profile a large js_run_devserver using the new watch protocol

[aspect-workflows]

Test

2 test targets passed

Targets

//js/private/test/js_run_devserver:js_run_devserver_test [k8-fastbuild]                 261ms
//js/private/test/js_run_devserver:node_modules_symlink_to_execroot_test [k8-fastbuild] 197ms

Total test execution time was 458ms. 223 tests (99.1%) were fully cached saving 33s.

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Test

e2e/bzlmod

All tests were cache hits

5 tests (100.0%) were fully cached saving 539ms.

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Test

e2e/gyp_no_install_script

All tests were cache hits

2 tests (100.0%) were fully cached saving 184ms.

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Test

e2e/js_image_oci

All tests were cache hits

1 test (100.0%) was fully cached saving 6s.

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Test

e2e/npm_link_package

All tests were cache hits

3 tests (100.0%) were fully cached saving 533ms.

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Test

e2e/npm_link_package-esm

All tests were cache hits

3 tests (100.0%) were fully cached saving 630ms.

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Test

e2e/npm_translate_lock

All tests were cache hits

1 test (100.0%) was fully cached saving 31ms.

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Test

e2e/npm_translate_lock_empty

All tests were cache hits

1 test (100.0%) was fully cached saving 31ms.

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Test

e2e/npm_translate_lock_multi

All tests were cache hits

2 tests (100.0%) were fully cached saving 268ms.

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Test

e2e/npm_translate_lock_partial_clone

All tests were cache hits

1 test (100.0%) was fully cached saving 31ms.

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Test

e2e/npm_translate_lock_replace_packages

All tests were cache hits

3 tests (100.0%) were fully cached saving 269ms.

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Test

e2e/npm_translate_lock_subdir_patch

All tests were cache hits

1 test (100.0%) was fully cached saving 73ms.

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Test

e2e/npm_translate_package_lock

All tests were cache hits

1 test (100.0%) was fully cached saving 31ms.

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Test

e2e/npm_translate_yarn_lock

All tests were cache hits

1 test (100.0%) was fully cached saving 31ms.

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Test

e2e/package_json_module

All tests were cache hits

1 test (100.0%) was fully cached saving 324ms.

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Test

e2e/pnpm_lockfiles

All tests were cache hits

52 tests (100.0%) were fully cached saving 6s.

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Test

e2e/pnpm_workspace

All tests were cache hits

15 tests (100.0%) were fully cached saving 2s.

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Test

e2e/pnpm_workspace_rerooted

All tests were cache hits

15 tests (100.0%) were fully cached saving 2s.

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Test

e2e/repo_mapping

All tests were cache hits

3 tests (100.0%) were fully cached saving 410ms.

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Test

e2e/rules_foo

All tests were cache hits

2 tests (100.0%) were fully cached saving 137ms.

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Test

e2e/runfiles

All tests were cache hits

1 test (100.0%) was fully cached saving 107ms.

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Test

e2e/vendored_node

All tests were cache hits

1 test (100.0%) was fully cached saving 114ms.

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