Limiting access to streaming memory in a stream in the GHC

Question

I am wondering if it is possible to limit the amount of memory that the stream uses? I am looking at starting a server on which an unreliable user code is presented and running. I can use SafeHaskell to ensure that it does not perform unauthorized I / O, but I need to make sure that the user code does not break the entire server, i.e. Causes a stack overflow or memory heap error. / p>

Is there a way to limit the amount of memory that each individual thread can access, or to somehow guarantee that if one thread consumes a huge amount of memory, then only this thread terminates?

Perhaps there is a way when any thread encounters an error out of memory, I can catch the exception and choose which thread is dying?

I talk more about concurrency, in the sense of forkIO and STM streams, and not about parallelism with par and seq.

Note: this is very similar to this question , but it never received an answer to the general problem, and the answers concerned a specific scenario of the question. Also, is it possible that something could happen in GHC 7.8 from 2011, maybe with a new I / O manager?

Answer 1

I do not know about Haskell, but in general, the answer to your question is no. In all programming languages ​​/ runtime / operating systems, etc. what I know, threads are nothing but different execution paths through the same code. In this case, it is important that threads always use the same virtual address space.

There is no technical reason why the memory allocator in your particular language and runtime system could not use a thread-specific variable to track how much was allocated by that thread and to impose an arbitrary limit.

There are no technical reasons why this could not be done, but if stream A selects an object that stream B subsequently accesses, stream C, stream D, ... Then what is the point of it to punish thread A for highlighting his? There is no practical way to track the "ownership" of an object that many threads access in the general case, so none of the languages ​​/ runtimes / OSes / etc. what I know about trying to do this.