Thanks; I will (continue) looking at these..... On Tue, Mar 27, 2012 at 1:42 PM, Paolo Castagna < castagna.li...@googlemail.com> wrote:
> Hi Bernie, > perhaps you can have a look at two or three small test programs in the TDB > test suite which run read/write transactions concurrently. > > If you want, you could try to run them and see if they give you a problem > or check if there is anything you do which is significantly different and > try to replicate your usage scenario there: > > > https://svn.apache.org/repos/asf/incubator/jena/Jena2/TDB/tags/jena-tdb-0.9.0-incubating/src/test/java/com/hp/hpl/jena/tdb/transaction/T_TransSystemMultiDatasets.java > > https://svn.apache.org/repos/asf/incubator/jena/Jena2/TDB/tags/jena-tdb-0.9.0-incubating/src/test/java/com/hp/hpl/jena/tdb/transaction/T_TransSystem.java > > https://svn.apache.org/repos/asf/incubator/jena/Jena2/TDB/tags/jena-tdb-0.9.0-incubating/src/test/java/com/hp/hpl/jena/tdb/transaction/T_TxnDeadlockTest.java > > Paolo > > Bernie Greenberg wrote: > > I don't know (businesswise) if I can post my stack trace or details of my > > code, but, first of all, my coworker was testing the code I had modified; > > he didn't write any new code, he just operated its UI correctly. > > > > One thread was in "begin(WRITE); make model; add assertions; commit; > > end()" on the dataset, and the other attempted to" begin(READ); construct > > map; end()," but instead of waiting in begin(READ), caused the thread > with > > the write-lock to crash. The cited URL addresses a type of abuse of > which > > I wouldn't dream, if I understand it correctly (one thread exploiting > > another's ownership of the database). I would expect that, with no > further > > code, a thread doing a begin(READ) should wait for a thread that > > successfully executed begin(WRITE) to exit from end() before the > > begin(READ) returns to its caller; is this not so? > > > > If you truly need more stack trace, I'll see what I can do. > > > > Bernie > > > > On Mon, Mar 26, 2012 at 4:40 PM, Andy Seaborne <a...@apache.org> wrote: > > > >> On 26/03/12 16:13, Bernie Greenberg wrote: > >> > >>> The new transaction primitives worked superlatively for me, but not > for my > >>> coworker testing my code. As soon as he issued a query while updates > were > >>> going on, the latter crashed. mid-transaction. > >>> > >>> Does dataset.begin/dataset.end provide, in addition to transaction > safety, > >>> thread synchronization/locking as well (as I imagine(d)), or must I > wrap > >>> Jena critical sections around each such pair if that is what I expect? > (In > >>> either case, the doc for begin/end should say). > >>> > >>> Thanks, > >>> Bernie > >>> > >>> > >> Bernie, > >> > >> Do you have a test case or details of the crash? > >> > >> Within a transaction all access must be multi-reader or single-writer. > The > >> normal pattern is one thread, one transaction. > >> > >> http://incubator.apache.org/**jena/documentation/tdb/tdb_** > >> transactions.html#multi-**threaded_use< > http://incubator.apache.org/jena/documentation/tdb/tdb_transactions.html#multi-threaded_use > > > >> > >> How is your coworker's testign using the transaction mechanism? > >> > >> Andy > >> > > >
