Re: what does transaction.abort() refresh?

On Wed, Oct 5, 2016 at 5:49 PM, Boylan, Ross <[email protected]> wrote:
> How do I know if I have the threaded transaction manager?

If you use the begin, abort, or commit functions in the transaction
manager, you're using the thread-local ("threaded" was a brain fart,
sorry) transaction manager. Similarly, if you create a connection by
calling open on a database without arguments, then the connection is
using a thread-local transaction manager.  You are doing those things
below, so both the connection and the code are using the same
transaction manager.


>  I just did import transaction.
> The other thread does NOT reassign conn.root.x; it gets x, modifies it, and commits.
>
> BTW, I'm only using threads as a warmup; eventually it will be zeo from different processes (probably).
>
> Here's the business end of the code that worked.  The version that didn't work used the commented out
>  aVariant.add(aRun) instead of the retrieval through the root object.
>
> #! /usr/bin/python3
> import pdb
> from persistent import Persistent
> from datetime import datetime
> from BTrees.IOBTree import IOBTree
> import sys, threading, time, transaction, ZODB
>
> # class definitions omitted; all are subclasses of Persistent
> ___def tickle(i, me, you):
>     start = datetime.now()
>     conn = db.open()
>     if i==1:
>         aManager = Manager()
>         conn.root.manager = aManager
>         aVariant = Variant(1)
>         aManager.addVariant(aVariant)
>         transaction.commit()
>         print("added variant")
>         you.release()
>         me.acquire()
>     else:
>         me.acquire()
>         aManager = conn.root.manager
>         aVariant = aManager._variants[1]
>     transaction.abort()
>     aRun = OneRun(i, start, datetime.now(), 0)
>     # not aVariant.add(aRun)
>     conn.root.manager._variants[1].add(aRun)
>     print(i)
>     transaction.commit()
>     you.release()
>     me.acquire()
>     transaction.abort()
>     aRun = OneRun(i+2, start, datetime.now(), 0)
>     print(i+2)
>     # not aVariant.add(aRun)
>     conn.root.manager._variants[1].add(aRun)
>     transaction.commit()
>     you.release()
>     me.acquire()
>     transaction.abort()
>     if i==1:
>         conn.root.manager.dump(sys.stdout)
>     conn.close()
>     you.release()
>
> db= ZODB.DB(dbname)
> l1 = threading.Lock()
> l2 = threading.Lock()
> l1.acquire()
> l2.acquire()
> t1 = threading.Thread(target=tickle, args=(1, l1, l2))
> t2 = threading.Thread(target=tickle, args=(2, l2, l1))
> t1.start()
> t2.start()
> t1.join()
> t2.join()
> db.close()

This code is rather complicated and leaves out a lot of details. I
could ask questions, but that would lead to more questions and
probably not a good use of time. :)

The short answer is that your gemstone mental model is correct.  If
you're getting different behavior, it's likely due to an issue with
your code.

Jim

-- 
Jim Fulton
http://jimfulton.info

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