How to Reproduce the Crash

Oct 13, 2025 by magicalceylontours.com 5 views

Introduction

When testing a server, it's not uncommon to encounter crashes or segmentation faults. In this article, we'll delve into the world of server testing and explore the common pitfalls that can lead to crashes. We'll also provide a step-by-step guide on how to reproduce the crash and offer solutions to resolve the issue.

How to Reproduce the Crash

To reproduce the crash, we'll use the server.fetch(request) method in our test code. The server file only has a simple route defined:

export const server = Bun.serve({
  routes: {
    "/": () => Response.json({ ok: true }),
  },

  port: process.env.PORT ?? 3000,
});

This code creates a server that listens on port 3000 and returns a JSON response with the key-value pair { ok: true }.

Relevant Log Output

The log output is empty, indicating that there are no error messages or warnings that can help us diagnose the issue.

Stack Trace (bun.report)

The stack trace is a crucial piece of information that helps us understand the sequence of events leading up to the crash. Here's the stack trace:

Bun v1.2.5 ([`013fddd`](<https://github.com/oven-sh/bun/tree/013fdddc6ed18bc849614ccb37a296fa0f69a5db>)) on macos aarch64 [TestCommand]

Segmentation fault at address 0x00000000

- *1 unknown/js code*
- `DebugHTTPSServerPrototype__doFetch`
- `DebugHTTPSServerPrototype__doFetch`
- `WebCore::DebugHTTPServerPrototype__fetchCallback`
- *1 unknown/js code*
- `jsc_llint_commonCallOp__llintOpWithMetadata__llintOpWithReturn__llintOp__commonOp__fn__fn__makeReturn__fn__fn__fn__666_callHelper__dispatch_LowLevelInterpreter64_asm_2535`
- `jsc_llint_commonCallOp__llintOpWithMetadata__llintOpWithReturn__llintOp__commonOp__fn__fn__makeReturn__fn__fn__fn__666_callHelper__dispatch_LowLevelInterpreter64_asm_2535`
- `jsc_llint_commonCallOp__llintOpWithMetadata__llintOpWithReturn__llintOp__commonOp__fn__fn__makeReturn__fn__fn__fn__684_callHelper__dispatch_LowLevelInterpreter64_asm_2535`
- `llint_call_javascript`
- `JSC::Interpreter::executeCall`

Features: tsconfig, tsconfig\_paths, http\_server, jsc

<!-- from bun.report: bJ4iMTjwjmHoHSkBnWfg -->

<sub>Sentry Issue: <strong><a href="https://bun-p9.sentry.io/issues/6324551853/">BUN-D2G</a></strong></sub>

Understanding the Stack Trace

The stack trace indicates that the crash occurs when calling the server.fetch(request) method. The sequence of events leading up to the crash is as follows:

The server.fetch(request) method is called.
The DebugHTTPSServerPrototype__doFetch function is executed.
The DebugHTTPSServerPrototype__doFetch function calls the WebCore::DebugHTTPServerPrototype__fetchCallback function.
The WebCore::DebugHTTPServerPrototype__fetchCallback function calls the jsc_llint_commonCallOp__llintOpWithMetadata__llintOpWithReturn__llintOp__commonOp__fn__fn__makeReturn__fn__fn__fn__666_callHelper__dispatch_LowLevelInterpreter64_asm_2535 function.
The jsc_llint_commonCallOp__llintOpWithMetadata__llintOpWithReturn__llintOp__commonOp__fn__fn__makeReturn__fn__fn__fn__666_callHelper__dispatch_LowLevelInterpreter64_asm_2535 function calls the jsc_llint_commonCallOp__llintOpWithMetadata__llintOpWithReturn__llintOp__commonOp__fn__fn__makeReturn__fn__fn__fn__666_callHelper__dispatch_LowLevelInterpreter64_asm_2535 function.
The jsc_llint_commonCallOp__llintOpWithMetadata__llintOpWithReturn__llintOp__commonOp__fn__fn__makeReturn__fn__fn__fn__666_callHelper__dispatch_LowLevelInterpreter64_asm_2535 function calls the jsc_llint_commonCallOp__llintOpWithMetadata__llintOpWithReturn__llintOp__commonOp__fn__fn__makeReturn__fn__fn__fn__684_callHelper__dispatch_LowLevelInterpreter64_asm_2535 function.
The jsc_llint_commonCallOp__llintOpWithMetadata__llintOpWithReturn__llintOp__commonOp__fn__fn__makeReturn__fn__fn__fn__684_callHelper__dispatch_LowLevelInterpreter64_asm_2535 function calls the llint_call_javascript function.
The llint_call_javascript function calls the JSC::Interpreter::executeCall function.

Solutions to Resolve the Issue

Based on the stack trace, we can identify several potential solutions to resolve the issue:

Update the Bun version: The stack trace indicates that the crash occurs in the Bun v1.2.5 version. We can try updating to a newer version of Bun to see if the issue is resolved.
Disable the DebugHTTPSServerPrototype__doFetch function: The stack trace indicates that the crash occurs when calling the DebugHTTPSServerPrototype__doFetch function. We can try disabling this function to see if the issue is resolved.
Fix the jsc_llint_commonCallOp__llintOpWithMetadata__llintOpWithReturn__llintOp__commonOp__fn__fn__makeReturn__fn__fn__fn__666_callHelper__dispatch_LowLevelInterpreter64_asm_2535 function: The stack trace indicates that the crash occurs when calling the jsc_llint_commonCallOp__llintOpWithMetadata__llintOpWithReturn__llintOp__commonOp__fn__fn__makeReturn__fn__fn__fn__666_callHelper__dispatch_LowLevelInterpreter64_asm_2535 function. We can try fixing this function to see if the issue is resolved.
Use a different testing framework: The stack trace indicates that the crash occurs when using the server.fetch(request) method. We can try using a different testing framework to see if the issue is resolved.

Conclusion

Q&A: Frequently Asked Questions

Q: What is the cause of the crash when testing a server? A: The cause of the crash can vary depending on the specific testing scenario and the server being tested. However, common causes of crashes include:

Incompatible dependencies: Conflicting dependencies between the server and the testing framework can lead to crashes.
Incorrect configuration: Misconfigured server settings or testing framework settings can cause crashes.
Insufficient resources: Insufficient system resources, such as memory or CPU, can cause crashes.

Q: How can I reproduce the crash? A: To reproduce the crash, follow these steps:

Create a simple server: Create a simple server using a framework like Bun or Express.
Write a test: Write a test that calls the server's API using a testing framework like Jest or Mocha.
Run the test: Run the test and observe the crash.

Q: What are the common symptoms of a crash when testing a server? A: Common symptoms of a crash when testing a server include:

Segmentation fault: A segmentation fault occurs when the server attempts to access memory that is not allocated to it.
Stack overflow: A stack overflow occurs when the server's stack is exhausted due to excessive function calls.
System crash: A system crash occurs when the server crashes the entire system.

Q: How can I debug a crash when testing a server? A: To debug a crash when testing a server, follow these steps:

Enable debugging: Enable debugging in the server and testing framework to collect more information about the crash.
Collect logs: Collect logs from the server and testing framework to identify the cause of the crash.
Use a debugger: Use a debugger to step through the code and identify the line that causes the crash.

Q: What are the best practices for testing a server? A: Best practices for testing a server include:

Write comprehensive tests: Write comprehensive tests that cover all aspects of the server's API.
Use a testing framework: Use a testing framework like Jest or Mocha to write and run tests.
Test for edge cases: Test for edge cases, such as invalid input or unexpected behavior.

Q: How can I prevent crashes when testing a server? A: To prevent crashes when testing a server, follow these best practices:

Use a testing framework: Use a testing framework like Jest or Mocha to write and run tests.
Test for edge cases: Test for edge cases, such as invalid input or unexpected behavior.
Use a debugger: Use a debugger to step through the code and identify potential issues.

Q: What are the common tools used for testing a server? A: Common tools used for testing a server include:

Jest: Jest is a popular testing framework for JavaScript.
Mocha: Mocha is a popular testing framework for JavaScript.
Bun: Bun is a popular server framework for JavaScript.
Express: Express is a popular server framework for JavaScript.

Q: How can I optimize my server testing? A: To optimize your server testing, follow these best practices:

Use a testing framework: Use a testing framework like Jest or Mocha to write and run tests.
Test for edge cases: Test for edge cases, such as invalid input or unexpected behavior.
Use a debugger: Use a debugger to step through the code and identify potential issues.

Conclusion

In this article, we've covered frequently asked questions about crashes when testing a server. We've provided best practices for testing a server, common tools used for testing a server, and tips for optimizing server testing. By following these best practices and using the right tools, you can ensure that your server testing is reliable and efficient.