Latency spikes in Jest tests under concurrent execution

When running Jest tests with concurrent execution enabled, latency spikes occur under high concurrency. The issue is observed when multiple test files are executed simultaneously, leading to increased test execution times and inconsistent performance.

The problem appears to be related to resource contention, such as CPU, memory, or I/O bottlenecks, which become more pronounced under concurrent test execution. Adjusting the maxConcurrency option in the Jest configuration or using the runInBand option to run tests sequentially can help isolate the impact of concurrency.

However, running tests sequentially can significantly increase total test execution time, especially for large test suites. The goal is to identify the root cause of the latency spikes and find a balance between concurrent execution and performance.

• What is the optimal maxConcurrency value for the given test suite and system resources?
• How can resource contention be mitigated to improve test execution times under concurrent requests?
• Are there specific test files or test cases that contribute more to the latency spikes under concurrency?