[qa] Refactor RPCTestHandler to prevent TimeoutExpired

qa/pull-tester/rpc-tests.py

@@ -251,21 +251,27 @@ class RPCTestHandler:
             self.num_running += 1
             t = self.test_list.pop(0)
             port_seed = ["--portseed=%s" % len(self.test_list)]
+            log_stdout = tempfile.SpooledTemporaryFile(max_size=2**16)
+            log_stderr = tempfile.SpooledTemporaryFile(max_size=2**16)
             self.jobs.append((t,
                               time.time(),
                               subprocess.Popen((RPC_TESTS_DIR + t).split() + self.flags + port_seed,
                                                universal_newlines=True,
-                                               stdout=subprocess.PIPE,
+                                               stdout=log_stdout,
-                                               stderr=subprocess.PIPE)))
+                                               stderr=log_stderr),
+                              log_stdout,
+                              log_stderr))
         if not self.jobs:
             raise IndexError('pop from empty list')
         while True:
             # Return first proc that finishes
             time.sleep(.5)
             for j in self.jobs:
-                (name, time0, proc) = j
+                (name, time0, proc, log_out, log_err) = j
                 if proc.poll() is not None:
-                    (stdout, stderr) = proc.communicate(timeout=3)
+                    log_out.seek(0), log_err.seek(0)
+                    [stdout, stderr] = [l.read().decode('utf-8') for l in (log_out, log_err)]
+                    log_out.close(), log_err.close()
                     passed = stderr == "" and proc.returncode == 0
                     self.num_running -= 1
                     self.jobs.remove(j)