CODEWITHSUNDEEP
pythonpython-3.xmultiprocessingpython-multiprocessing
Xavi
Xavi

Reputation: 149

Passing result-list from Multiprocessing Manager outside scope

I'm trying to scan domain for pentesting purposes, the program use Multiprocessing with the result-list got passed from Processes; back to main function.

I have tried to use Global Variables mentioned in global also in a class. Using this reminds me that the processes lives in different memory. So i'm using manager.list() instead; to share memory between processes

Here's what i've tried:

from multiprocessing import Process, cpu_count, Manager

class variably:
    variably=bla..
    .... 

def engine(domainlist, R):
    for domain in domainlist:
        try:
            r = requests.get("http://" + domain, headers=headers, timeout=0.7, allow_redirects=False)
            if r.status_code == expected_response:
                print("Success" + domain)
                print(domain, file=open("LazyWritesForDebugPurposes.txt", "a"))
                R.append(str(domain))
            elif r.status_code != expected_response:
                print("Failed" + domain + str(r.status_code))

        except:
            pass

def fromtext():
    ....
    R = []
    with Manager() as manager:
        num_cpus = cpu_count()
        processes = []
        R = manager.list()
        for process_num in range(num_cpus):
            section = domainlist[process_num::num_cpus]
            p = Process(target=engine, args=(section,R,))
            p.start()
            processes.append(p)
        for p in processes:
            p.join()
        print(R)
    print(R)

    print("")
    print(" Total of Domains Queried : "  + colors.RED_BG + " "+str(len(R)) +" "+ colors.ENDC)
    if len(inf.result_success) >= 0:
        print(" Successfull Result : " + colors.GREEN_BG + " "+str(len(R))+ " "+colors.ENDC)
fromtext()

Sorry for any invalid syntax or indentation, trying to simplify the codes into more shorter snippet.

Above codes returns BrokenPipe sometimes with ConnectionRefused error. From the exception, i can see that the list already appended as: ['Domain.com','Domain_2.com'] but somehow raises an exception.

Here's some Screenshot about the problem: Problematic Screenshot

EDIT:

It's looks like the list can only pass inside manager() scope, how can i extend the data passing outside the scope, for example calling the list in different function. This below codes works:

    with Manager() as manager:
        num_cpus = cpu_count()
        processes = []
        R = manager.list()
        for process_num in range(num_cpus):
            section = domainlist[process_num::num_cpus]
            p = Process(target=engine, args=(section,R,))
            p.start()
            processes.append(p)
        for p in processes:
            p.join()

        str(len(R))

Upvotes: 0

Views: 405

Answers (2)

Xavi
Xavi

Reputation: 149

The problem to this that i had to explicitly convert the manager.list() as another normal list by setting a new variable and use global to make it usable in another function. I know that it's dirty, havent tried using Queue() but for now, atleast it's working.

def executor():
    global R
    .... 
    with Manager() as manager:
        num_cpus = cpu_count()
        processes = []
        R = manager.list()
        for process_num in range(num_cpus):
            section = domainlist[process_num::num_cpus]
            p = Process(target=engine, args=(section,R,))
            p.start()
            processes.append(p)
        for p in processes:
            p.join()

        R = list(R)

    print(R)

If there's a simplification to this, i would really appreciate it.

Upvotes: 0

Frank Yellin
Frank Yellin

Reputation: 11307

You really want to use a queue. Create a multiprocessing.SimpleQueue in your main thread and pass it to all your subprocesses. They can add items to this queue.

Creating your own manager is almost always a mistake.

Upvotes: 1

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