perf: optimize JS tracer performance by reusing objects #305
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This change eliminates the performance bottleneck in JavaScript tracing where new objects were created for every EVM instruction execution. Key improvements: - Added object reuse pattern with lazy initialization for step and database objects - Implemented create_js_object_template() and update_js_object() methods - Modified try_step() and try_fault() to reuse objects instead of recreating - Reduced object allocation from millions per trace to 2 per tracer instance - Added comprehensive test suite with 38 new tests covering unit, integration, and performance scenarios Performance impact: - Before: 2 new JS objects created per EVM instruction (potentially millions per transaction) - After: 2 JS objects created once per tracer instance, then updated in-place - Expected: Significant reduction in allocation overhead and garbage collection pressure Backward compatibility maintained - existing JavaScript tracer code works unchanged.
- Add enter_frame_object and exit_frame_object fields to JsInspector - Implement create_js_object_template and update_js_object for CallFrame and FrameResult - Update try_enter and try_exit to use lazy initialization and object reuse - Add comprehensive tests for enter/exit optimization - This completes the object reuse pattern for all JS tracer hot paths
- Replace assert_eq with assert for boolean comparisons - Use inline format args - Add #[allow(dead_code)] to unused into_js_object methods
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Summary
This PR addresses a significant performance bottleneck in the JavaScript tracer implementation where new JS objects were created for every EVM instruction execution. The optimization introduces an object reuse pattern that dramatically reduces allocation overhead.
Changes
Core Implementation
step_objectanddb_objectfields toJsInspectorstruct for reusable objectscreate_js_object_template()methods for one-time object structure creationupdate_js_object()methods for in-place data updates without recreationtry_step()andtry_fault()methods to use lazy initialization and object reusePerformance Optimization
Test Coverage
Backward Compatibility
All existing JavaScript tracer code continues to work unchanged. The original
into_js_object()methods are preserved for compatibility.Test Results
All 46 tests pass, including 8 existing tests and 38 new tests specifically for this optimization.
Type of Change