- added a mutex to the mapper compilation step. ive been reluctant to add any kind

of threading anything to SA but this is one spot that its its really needed since mappers
are typically "global", and while their state does not change during normal operation, the
initial compilation step does modify internal state significantly, and this step usually
occurs not at module-level initialization time (unless you call compile()) but at first-request
time
- added "compile_mappers()" function as a shortcut to compiling all mappers

1 files changed, 70 insertions, 0 deletions

diff --git a/test/perf/threaded_compile.py b/test/perf/threaded_compile.py
new file mode 100644
index 000000000..3c521f231
--- /dev/null
+++ b/test/perf/threaded_compile.py
@@ -0,0 +1,70 @@
+# tests the COMPILE_MUTEX in mapper compilation
+
+from sqlalchemy import *
+import thread, time, random
+from sqlalchemy.orm import mapperlib
+
+meta = BoundMetaData('sqlite:///foo.db')
+
+t1 = Table('t1', meta, 
+    Column('c1', Integer, primary_key=True),
+    Column('c2', String(30))
+    )
+    
+t2 = Table('t2', meta,
+    Column('c1', Integer, primary_key=True),
+    Column('c2', String(30)),
+    Column('t1c1', None, ForeignKey('t1.c1'))
+)
+meta.create_all()
+
+class T1(object):
+    pass
+
+class T2(object):
+    pass
+    
+class FakeLock(object):
+    def acquire(self):pass
+    def release(self):pass
+
+# uncomment this to disable the mutex in mapper compilation;
+# should produce thread collisions    
+#mapperlib._COMPILE_MUTEX = FakeLock()
+
+existing_compile_all = mapperlib.Mapper._compile_all
+state = [False]
+# decorate mapper's _compile_all() method; the mutex in mapper.compile()
+# should insure that this method is only called once by a single thread only
+def monkeypatch_compile_all(self):
+    if state[0]:
+        raise "thread collision"
+    state[0] = True
+    try:
+        print "compile", thread.get_ident()
+        time.sleep(1 + random.random())
+        existing_compile_all(self)
+    finally:
+        state[0] = False
+mapperlib.Mapper._compile_all = monkeypatch_compile_all
+
+def run1():
+    print "T1", thread.get_ident()
+    class_mapper(T1)
+
+def run2():
+    print "T2", thread.get_ident()
+    class_mapper(T2)
+
+for i in range(0,1):
+    clear_mappers()
+    mapper(T1, t1, properties={'t2':relation(T2, backref="t1")})
+    mapper(T2, t2)
+    #compile_mappers()
+    print "START"
+    for j in range(0, 5):
+        thread.start_new_thread(run1, ())
+        thread.start_new_thread(run2, ())
+    print "WAIT"
+    time.sleep(5)
+