Mixed Lazy Bytestrings when concurrent write to Handle about bytestring HOT 2 CLOSED

Correct me if I'm wrong but this is exactly the same behaviour as you'll get with hPutStr for String. Try it with long enough strings, or go look at the impl, it also releases the Handle lock. In fact, last time I checked the Handle code, it goes to quite some lengths to make sure that it is not evaluating arbitrary user thunks while it is holding the Handle lock.

In other words, this would be the expected behaviour. Given that evaluating the next chunk can take arbitrary time, releasing the handle lock and allowing interleaving seems like the right thing to do. Are there compelling reasons we'd want to change that?

If you really want to write multiple streams to one Handle concurrently without any coordination, you can at least control the chunk boundaries. But I'd suggest the better approach is to use your own MVar in your app. Then you're also responsible for making sure the lock is released if one of the writers goes off and sleeps while evaluating the next chunk.

from bytestring.

I get your point. The one reason I can come up with for changing the behavior is "it is closer to what the strict hPut does". I think I ended up going for an MVar, which is probably the easiest solution. I opened #82 which documents the current behavior. I think it can be useful. No hard feelings if you decline or reword it.

from bytestring.