tests/thread: Add tests for running GC within a thread, and heap stress.

tests/thread/thread_gc1.py

+# test that we can run the garbage collector within threads
+#
+# MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
+
+import gc
+import _thread
+
+def thread_entry(n):
+    # allocate a bytearray and fill it
+    data = bytearray(i for i in range(256))
+
+    # do some work and call gc.collect() a few times
+    for i in range(n):
+        for i in range(len(data)):
+            data[i] = data[i]
+        gc.collect()
+
+    # print whether the data remains intact and indicate we are finished
+    with lock:
+        print(list(data) == list(range(256)))
+        global n_finished
+        n_finished += 1
+
+lock = _thread.allocate_lock()
+n_thread = 4
+n_finished = 0
+
+# spawn threads
+for i in range(n_thread):
+    _thread.start_new_thread(thread_entry, (10,))
+
+# busy wait for threads to finish
+while n_finished < n_thread:
+    pass

tests/thread/thread_stress_heap.py

+# stress test for the heap by allocating lots of objects within threads
+# allocates about 5mb on the heap
+#
+# MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
+
+import _thread
+
+def last(l):
+    return l[-1]
+
+def thread_entry(n):
+    # allocate a bytearray and fill it
+    data = bytearray(i for i in range(256))
+
+    # run a loop which allocates a small list and uses it each iteration
+    lst = 8 * [0]
+    sum = 0
+    for i in range(n):
+        sum += last(lst)
+        lst = [0, 0, 0, 0, 0, 0, 0, i + 1]
+
+    # check that the bytearray still has the right data
+    for i, b in enumerate(data):
+        assert i == b
+
+    # print the result of the loop and indicate we are finished
+    with lock:
+        print(sum, lst[-1])
+        global n_finished
+        n_finished += 1
+
+lock = _thread.allocate_lock()
+n_thread = 10
+n_finished = 0
+
+# spawn threads
+for i in range(n_thread):
+    _thread.start_new_thread(thread_entry, (10000,))
+
+# busy wait for threads to finish
+while n_finished < n_thread:
+    pass