eventlog to report more information about stopping threads because of FFI calls
Currently eventlog file doesn't contain more information about FFI than:
"stopping thread ### (making a foreign call)"
It would be very-very useful if we know what actual foreign calls are made. For example:
"stopping thread ### (making a foreign call to function YYYY)
So we could see which function and how much time is spent on that call. If creation of threads because of in-bound foreign calls (callbacks) have which callbacks are created for it will be very useful, too.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 8.0.2 |
| Type | FeatureRequest |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Profiling |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | Unknown/Multiple |
| Architecture |
Activity
added Tfeature request Trac import profiling labels
Attached file
Core88_threadprofile.png(download).
How do you propose we would identify which foreign function is being called? I can think of a few ways,
- Have the compiler produce a string which is passed to the RTS when generating code for safe foreign calls
- Use the symbol table lookup of the callee's address
- Use DWARF information of the callee's address
All of these have their costs and I do wonder whether this sort of instrumentation might not be better left to the user to implement themselves with, e.g.
traceEvent, if they need it.I'm not aware of GHC architecture and cannot help with actual implementation much.
If there are many foreign calls or we're using third-party libraries, like wxHaskell - it will be hard to place traceEvent everywhere. Automated adding of such traceEvent could be very helpful, i.e. automated instrumentation.
About DWARF - there is no DWARF support under Windows, so this limit debugging capabilities.
added eventlog label
added Pnormal label
