suspending a thread and executing it later

Quoted 3 lines

Here is what I want to do... in my program, I want to arbitrarily in some function suspend the execution of the current (self) thread and schedule my self to resume from that point later.

Have a look at ``info libc "Non Local Exits" "System V Contexts"''. The basic idea is to have one ucontext per thread. When the running thread wants to block, it picks some other thread, and then swapcontext()s with it.

Quoted 5 lines

In my program, I only have 2 threads... and lets say thread 1 ends up calling a function foo() that will block on IO. I dont want to make the whole system block, so I want to resume the execution of foo() when the IO completes and restore thread state so that the stack (function call history and all) is maintained.

The easy way to do this is via pthreads, but if you really want to do it yourself, you'll probably need to set every file descriptor to non-block mode, and then swapcontext() whenever an IO function returns EAGAIN.

Steven Smith,
[email protected].