[bdbxml] memory leak and out of available locker entries

Hello,

We use dbxml v 1.2 in a production environment and have been experiencing a 
severe memory leak sometimes rendering the database unusable with db_recover 
returning "out of available locker entries".

We've tightened down everything that we could think of - 
calling .delete() and .close() on every XmlResults, XmlQueryContext and 
XmlDocument object. In fact, we even went as far as calling 
XmlDocument.getContentAsString() so that we could 
XmlDocument.delete(); 
XmlDocument.close(); 
XmlDocument=null

in case the XmlDocument objects were keeping handles open inside Db. 

We also close the XmlContainer objects by calling
XmlContainer.close();
XmlContainer = null;

We also implemented periodic checking on the transactions inside Dbxml by 
logging
log.info("txnStat:" + env.txnStat(Db.DB_STAT_CLEAR).toString());

which consistently produces something like:
INFO KaRMI SocketThread-4 com.lightspoke.dbx.dao.DbxContainerManager - 
txnStat:DbTxnStat:
st_last_ckp=com.sleepycat.db.DbLsn@2d802f
st_time_ckp=1125200718
st_last_txnid=-2147446531
st_maxtxns=20
st_naborts=0
st_nbegins=1
st_ncommits=1
st_nactive=0
st_nrestores=0
st_maxnactive=1
st_txnarray=
st_region_wait=0
st_region_nowait=4
st_regsize=16384

But just to be sure, we even force all transactions to commit periodically 
using the following code:

DbPreplist[] txnlst = env.txnRecover(maxWorkingTxn, Db.DB_FIRST);
log.info("txn list size: " + txnlst.length);
for (int t=0;t<txnlst.length;t++) {
txnlst[t].txn.commit(Db.DB_TXN_NOSYNC);
} //for txn

But this piece of code never executes because we never have an active 
transaction - which suggests that we are successfully committing all 
transactions we start.

The only object that we can see if being kept alive and out of the garbage 
collector is then the DbEnv object which stays in memory until we shut down 
our server wrapper around Dbxml. 

We instantiate it like this:

private int CFLAG = 
Db.DB_CREATE|Db.DB_INIT_LOCK|Db.DB_INIT_LOG|Db.DB_INIT_MPOOL|Db.DB_INIT_TXN;
env = new DbEnv(0);
env.setLockMaxLockers(dbMaxLockers);
env.setLockMaxLocks(dbLockMaxLocks);
env.setLockMaxObjects(dbLockMaxObjects);
env.setCacheSize( dbCacheSize, dbCacheNum );
env.setLockDetect(Db.DB_LOCK_OLDEST);
env.setErrorStream(System.err);
env.open( dbxmlpath , CFLAG , 0);
env.setErrorStream(System.err);

How do we go about finding where the memory consumption is happening? We've 
run Jprobe on the server wrapper around dbxml but the java portion of our 
code never goes beyond 50MB of memory usage according to Jprobe - while the 
jvm running the code can easily run up to 800MB after which it slows the 
entire server down to a crawl. Once we restart our wrapper (which closes the 
DbEnv object) we get all that memory back.

Any ideas on how to track this down or if we are missing something totally 
obvious would be greatly appreciated. 

Thank you in advance,

-Matthew

http://www.lightspoke.com
Lightspoke Web-based Database