Python Z3 和 concurrent.futures

Question

我想并行解决一组包含的问题，然后添加附加信息以解决新问题。

下面是用于解决问题的程序结构示例：

from z3 import *
import concurrent.futures


# solver test function
def add(a, b, solver, index):
    solver.append(a > b)
    assert solver.check()
    model = solver.model()
    return {
        'solver': solver,
        'av': model[a],
        'a': a,
        'b': b,
        'bv': model[b],
        'index': index
    }


with concurrent.futures.ThreadPoolExecutor(max_workers=5) as executor:
    # start solving the problems
    to_compute = []
    for i in range(3):
        sol = z3.Solver()
        to_compute.append(executor.submit(
            add,
            Int('a{}'.format(i)),
            Int('b{}'.format(i)),
            sol,
            i
        ))
    # wait for the solution to the computations
    next_to_solve = []
    for result_futures in concurrent.futures.as_completed(to_compute):
        results = result_futures.result()
        print(results)
        sol = results['solver']
        sol.append(results['a'] > results['av'])
        next_to_solve.append(
            executor.submit(
                add,
                results['a'],
                results['b'],
                sol,
                results['index']
            )
        )

每次程序的结果都不一样运行，结果包括：

Z3Exception 'invalid dec_ref command'
python 崩溃
没有错误

我需要做什么才能使程序更可靠？

Answer 1

你看到这个例子了吗：http://github.com/Z3Prover/z3/blob/master/examples/python/parallel.py

我不是 z3py 中并发特性的专家，但似乎您需要非常小心地在您作为运行求解器的同一上下文中创建变量。该文件中有一些提示。

Python Z3 和 concurrent.futures

Python Z3 and concurrent.futures

z3py

concurrent.futures