Determining the state of an LDAP connection

Question

Hi all,
I'm in a situation where I need to determine the state of an existing LDAP connection. The code is called from Java servlets / JSP's, and we're having a problem where the client mysteriously disconnects. The stack trace points to:
04/10/04 10:24:54 javax.naming.CommunicationException: connection closed. Root exception is java.io.IOException: connection closed
04/10/04 10:24:54 at com.sun.jndi.ldap.LdapClient.ensureOpen(LdapClient.java:1648)
04/10/04 10:24:54 at com.sun.jndi.ldap.LdapClient.search(LdapClient.java:594)
04/10/04 10:24:54 at com.sun.jndi.ldap.LdapCtx.doSearch(LdapCtx.java:1921)
04/10/04 10:24:54 at com.sun.jndi.ldap.LdapCtx.searchAux(LdapCtx.java:1783)
04/10/04 10:24:54 at com.sun.jndi.ldap.LdapCtx.c_search(LdapCtx.java:1708)
04/10/04 10:24:54 at com.sun.jndi.toolkit.ctx.ComponentDirContext.p_search(ComponentDirContext.java:368)
04/10/04 10:24:54 at com.sun.jndi.toolkit.ctx.PartialCompositeDirContext.search(PartialCompositeDirContext.java:328)
04/10/04 10:24:54 at com.sun.jndi.toolkit.ctx.PartialCompositeDirContext.search(PartialCompositeDirContext.java:313)
04/10/04 10:24:54 at javax.naming.directory.InitialDirContext.search(InitialDirContext.java:238)
04/10/04 10:24:54 at com.tekelec.corpdir.ad.ADHelper.getAvailableOrgUnits(ADHelper.java:582)
The peculiar thing is that the InitialDirContext DOES exist, and is not null. Since we can't poinpoint what is causing the disconnects, the next best thing is to to a test against the context to determine if it is still connected.
Looking at this stack trace, I can see a function: com.sun.jndi.ldap.LdapClient.ensureOpen(LdapClient.java:1648)
Googling the source, shows the following implementation:
private void ensureOpen() throws IOException {
     if (conn == null) {
     throw new IOException("connection closed");
However, this does no good, since the function is private, and the corresponding Connection object is not exposed through JNDI.
Does anyone have any ideas? For now, I'm going to just call a simple 'lookup(...)' to cause the exception to be thrown if the connection is dead.
TIA!
-Sean

Answer 1

I was getting this exception on relatively large searches (but not on smaller ones). I was also getting a java.lang.OutOfMemoryError just before it that wasn't part of the stack trace. The server was nowhere near running out of swap, and all the /etc/system parameters (solaris) were reasonable.
Then I found this page:
http://java.sun.com/docs/hotspot/PerformanceFAQ.html#171
and changed the way I'm calling the jvm this way:
/usr/local/j2sdk1.4.2_08/bin/java -Xms512m -Xmx512m <java class file>
This solved the problem for me. Something you may want to try, anyway.