I am trying to upgrade from jconn2 to jconn4. The issue that i am facing is that c3p0 is notworking as expected. Quick online search says that it supports jconn4 completely, but i get the below exception.
com.sybase.jdbc4.jdbc.SybSQLException: SQL Anywhere Error -685: Resource governor for 'prepared statements' exceeded
at com.sybase.jdbc4.tds.Tds.processEed(Tds.java:4003)
at com.sybase.jdbc4.tds.Tds.nextResult(Tds.java:3093)
at com.sybase.jdbc4.jdbc.ResultGetter.nextResult(ResultGetter.java:78)
at com.sybase.jdbc4.jdbc.SybStatement.nextResult(SybStatement.java:289)
at com.sybase.jdbc4.jdbc.SybStatement.nextResult(SybStatement.java:271)
at com.sybase.jdbc4.jdbc.SybStatement.queryLoop(SybStatement.java:2408)
at com.sybase.jdbc4.jdbc.SybStatement.executeQuery(SybStatement.java:2394)
at com.sybase.jdbc4.jdbc.SybPreparedStatement.executeQuery(SybPreparedStatement.java:257)
Any suggestions on how to tackle this issue??/
It looks like your issue is too many prepared statements open, relative to max_statement_count defined on your server.
The simplest thing to do would just be to turn Statement caching off in c3p0, i.e. make sure that the c3p0 properties maxStatements and maxStatementsPerConnection are set to 0. If you want the performance benefits of statement caching, make sure that maxStatements is set to a value significantly lower than the server-side max_statement_count. You could also turn the "resource governor" off by setting max_statement_count to zero, although Sybase seems to discourage that.
See also c3p0 docs re Statement caching.
Related
For the last few weeks, I have been trying to deal with an intermittent problem on a camel route using XSLT processing following aggregation. It is intermittent in the sence that while it frequently raises this exception, I can re-run the data extract and processing that failed a few seconds later and it usually succeeds. I have yet to find any data that fails consistently.
I am assuming that the aggregation is causing the problem, but I can't for the life of me understand why. I thought it might be the custom aggregation bean I was using, so I replaced it with XSLTAggreationStrategy, but it still intermittently gives this issue, either when further transforming the aggregated XML, or when just writing it out to the a file.
This is executing in an Apache-Karaf environment, and I have Camel-Saxon 2.21.2 and Apache ServiceMix Saxon-HE 9.8.0.8_1 bundles loaded.
Thanks for looking.
The abridged stack trace is:
...
Caused by: [java.lang.NullPointerException -
null]java.lang.NullPointerException
at net.sf.saxon.dom.DOMNodeWrapper$ChildEnumeration.skipFollowingTextNodes(DOMNodeWrapper.java:1149)
at net.sf.saxon.dom.DOMNodeWrapper$ChildEnumeration.next(DOMNodeWrapper.java:1178)
at net.sf.saxon.tree.util.Navigator$EmptyTextFilter.next(Navigator.java:1078)
at net.sf.saxon.tree.util.Navigator$AxisFilter.next(Navigator.java:1039)
at net.sf.saxon.tree.util.Navigator$AxisFilter.next(Navigator.java:1017)
at net.sf.saxon.expr.parser.ExpressionTool.effectiveBooleanValue(ExpressionTool.java:643)
at net.sf.saxon.expr.Expression.effectiveBooleanValue(Expression.java:532)
at net.sf.saxon.pattern.PatternWithPredicate.matches(PatternWithPredicate.java:141)
at net.sf.saxon.trans.Mode.searchRuleChain(Mode.java:570)
at net.sf.saxon.trans.Mode.getRule(Mode.java:476)
at net.sf.saxon.trans.Mode.applyTemplates(Mode.java:1041)
at net.sf.saxon.expr.instruct.ApplyTemplates.apply(ApplyTemplates.java:281)
at net.sf.saxon.expr.instruct.ApplyTemplates.processLeavingTail(ApplyTemplates.java:241)
at net.sf.saxon.expr.instruct.Template.applyLeavingTail(Template.java:239)
at net.sf.saxon.trans.Mode.applyTemplates(Mode.java:1057)
at net.sf.saxon.expr.instruct.ApplyTemplates.apply(ApplyTemplates.java:281)
at net.sf.saxon.expr.instruct.ApplyTemplates.process(ApplyTemplates.java:237)
at net.sf.saxon.expr.instruct.ElementCreator.processLeavingTail(ElementCreator.java:431)
at net.sf.saxon.expr.instruct.ElementCreator.processLeavingTail(ElementCreator.java:373)
at net.sf.saxon.expr.instruct.Template.applyLeavingTail(Template.java:239)
at net.sf.saxon.trans.Mode.applyTemplates(Mode.java:1057)
at net.sf.saxon.Controller.transformDocument(Controller.java:2080)
at net.sf.saxon.Controller.transform(Controller.java:1903)
at org.apache.camel.builder.xml.XsltBuilder.process(XsltBuilder.java:141)
at org.apache.camel.impl.ProcessorEndpoint.onExchange(ProcessorEndpoint.java:103)
at org.apache.camel.component.xslt.XsltEndpoint.onExchange(XsltEndpoint.java:138) ...
In 9.8.0.8, the class net.sf.saxon.dom.DOMNodeWrapper has only 1144 lines, so a stacktrace showing line 1178 suggests there's some kind of versioning problem.
The class DOMNodeWrapper was first introduced in 9.5 (previously it was called NodeWrapper), and the line numbers are just one off from those in the current 9.5 source, so I suspect what you have loaded is some sub-release of the 9.5 branch. Other line numbers in the stack trace are also consistent with this being 9.5.
That of course doesn't explain the problem, but it might give a clue.
My immediate instinct was that over the years since 9.5 we might have fixed a multi-threading bug. DOM is not thread-safe, so Saxon takes considerable care to synchronize its access. Saxon bug https://saxonica.plan.io/issues/2376 addresses this problem. On the 9.5 branch this was first fixed in maintenance release 9.5.1.11, so it's possible you don't have that patch. I think it would be useful to investigate why you are loading an old version of Saxon, and another useful angle would be to discover exactly which version it is (the static method net.sf.saxon.Version.getProductVersion() will give you this information.)
Incidentally, if you are using multi-threaded access to a DOM tree then you should ask yourself whether this is a good idea. Saxon access to DOM is slow at the best of times (compared to JDOM and XOM, let alone to Saxon's native tree model), and the lack of thread safety and the need for synchronisation makes it a pretty poor choice in a multi-threaded application.
Also, note that Saxon can synchronize its own access to the DOM, but it can't synchronize with third-party code that might also be using the DOM.
Currently i am using the REST interface to query vespa, which seems to work great but something tells me that i should be using searchers in the application to make the client(server side code) a bit lighter (bundle the jar file in the application package) to make it a bit smoother. I have managed to do some simple searcher/processor applications. But this is a bit overwhelming.
So are there any readily available examples ?
Basicially i want to:
Send to /search?query=someId
Do a ordinary search for the weighted set on this documentID (I guess this one can be handy: https://docs.vespa.ai/documentation/reference/inspecting-structured-data.html)
Take those items in the response and add it to a wand item(s) and query for a wand with wandsearcher on a given field. Similar to the yql:
"select * from sources * where wand(interest, some weightedsets));","ranking":"combined_score" and return the matches.
Just curious also, apart from the trouble of string building with the http request i am doing at the moment are there any performance gains of using a searcher or go the java route vs rest?
thanks for any insight or code help i can start with.
There is an example of using the WandItem (YQL wand)here https://docs.vespa.ai/documentation/advanced-ranking.html and see also https://docs.vespa.ai/documentation/using-wand-with-vespa.html as there are two wand implementations available in Vespa, it sounds from the description that the wand() is what you want to use for this use case. For the first call you probably want to have a dedicated document summary to reduce the amount of data fetched for your first query and also the option of serving it out of memory only (See https://docs.vespa.ai/documentation/document-summaries.html)
Also see https://docs.vespa.ai/documentation/searcher-development.html as a general resource on writing searchers.
For your use case it makes a lot of sense to write a searcher to perform these two queries as your second query depends on the first and you avoid the cost of rendering/http/yql parsing which might matter if your client is remote with high network latency.
I didn't have this problem before 4.x upgrade. The problem is that I have a field whose omitTermFreqAndPositions attribute is set to true for various reasons. When a user performs phrase query explicitly or implicitly, it failed silently in Solr 3.5 or 3.6 but not in 4.x.
What would be a way to avoid this? One obvious way to reset omitTermFreqAndPositions to false but that's something I would like to avoid. I heard about implementing some kind of custom similarity class for this particular field but I would like to understand it better (so any explanation about it would be great whether it can be a solution for my problem).
You can create your own requestHandler, where there you will catch this exception and ignore it silently. See here
I'm running into a strange issue on Vista with the Performance monitoring API. I'm currently using code that worked fine on XP/2k, based around PdhGetFormattedCounterValue(). I start out using PdhExpandWildCardPath to expand the counters (I'm interested in overall network statistics), the counters I'm looking at are:
\\Network Interface(*)\\Bytes Received/sec
\\Network Interface(*)\\Bytes Sent/sec
\\Processor(_Total)\\% Processor Time
The problem is that on their first call they return PDH_INVALID_DATA, I don't think this is a problem, since if I query it again I will start getting data without the error. The problem is this - while the processor time is worked exactly as expected, neither of the network interface counters are returning anything - just 0 all the time. I verified using Perfmon that they are reporting data normally, so I'm at a loss as to what might be the issue. I caught this at MS:
http://support.microsoft.com/?scid=kb%3Ben-us%3B287159&x=11&y=9
But I'm not interested in multi-language for my task, so I don't think this is relevant. I will see if I can come up with some basic code showing exactly what I'm doing, but nothing is returning anything strange, and it worked on XP/2k, so I suspect something changed under the hood. Thanks!
It turns out the issue was that the network interfaces are both wildcards, whereas the Processor one is actually already rolled up by the performance monitoring. What I didn't realize was that it PdhExpandWildCardPath didn't return something directly usable by PdhAddCounter. By this I mean that if ExpandWildCard returns 3 expanded matches, they come back as a null separated strings - I understood this, but I had assumed that AddCounter would be effectively create a counter containing all three. Nope, reality is I needed to break up each path and request it individually from AddCounter, then roll up the results manually when I get them.
Hopefully this helps someone else to avoid the same mistake I made with less frustration. ;)
When you take your first look at an Oracle database, one of the first questions is often "where's the alert log?". Grid Control can tell you, but its often not available in the environment.
I posted some bash and Perl scripts to find and tail the alert log on my blog some time back, and I'm surprised to see that post still getting lots of hits.
The technique used is to lookup background_dump_dest from v$parameter. But I only tested this on Oracle Database 10g.
Is there a better approach than this? And does anyone know if this still works in 11g?
Am sure it will work in 11g, that parameter has been around for a long time.
Seems like the correct way to find it to me.
If the background_dump_dest parameter isn't set, the alert.log will be put in $ORACLE_HOME/RDBMS/trace
Once you've got the log open, I would consider using File::Tail or File::Tail::App to display it as it's being written, rather than sleeping and reading. File::Tail::App is particularly clever, because it will detect the file being rotated and switch, and will remember where you were up to between invocations of your program.
I'd also consider locking your cache file before using it. The race condition may not bother you, but having multiple people try to start your program at once could result in nasty fights over who gets to write to the cache file.
However both of these are nit-picks. My brief glance over your code doesn't reveal any glaring mistakes.