Re: [basex-talk] Performance of PUL commit

Hi Marco,

There are two clients which read and write through RESTXQ to/from 2 different logical DBs on the same server. Is it possible that behaving concurrently we cause some sort of race condition that serializes operations for a long time period?

Yes, this is absolutely possible. I guess that your hard disk, or even SSD, needs to do many write operations at the same time, leading to a somewhat random access pattern.

You could try to set the PARALLEL flag to 1 and see how this effects the total performance!

Please help us out [...]

Hope this helps ;) Christian

because it's getting to deeply nested into BaseX's

internals for us to understand.

Thanks a lot and BR, Marco.

[1] https://github.com/BaseXdb/basex/blob/master/basex-core/src/main/java/org/ba... [2] public Iter iter() throws QueryException { compile();

long time = System.currentTimeMillis();
Util.errln("QUERY [MARCO]: Start query iter " + time);

try {
  [...]
  final Updates updates = resources.updates;
  if(updates != null) {
    // if parent context exists, updates will be performed by main

context Util.errln("QUERY [MARCO]: Starting updates " + (System.currentTimeMillis() - time)); if(qcParent == null) { [...] Util.errln("QUERY [MARCO]: Completed updates " + (System.currentTimeMillis() - time)); } } Util.errln("QUERY [MARCO]: Completed query" + (System.currentTimeMillis() - time)); return cache;

} catch(final StackOverflowError ex) {
  [...]

}

}

On 22/02/2015 22:08, Marco Lettere wrote:

...

I'm planning to add some logging here [1] and here [2]. Do you think it will unleash some details? M.

[1] https://github.com/BaseXdb/basex/blob/master/basex-api/src/main/java/org/bas... [2] https://github.com/BaseXdb/basex/blob/master/basex-core/src/main/java/org/ba...

On 22/02/2015 20:05, Christian Grün wrote:

...

...

I'd like just to understand to what relates the huge difference (d) between "querying the db and scheduling an update to the PUL" which is what the internal function does and the time logged by the basexhttp server as the completion time of the whole RestXQ call which is T + d.

Hm, difficult to tell. In all cases, the PUL will be executed before the result of a query will be sent to the client.