Hi,
I'm having issue an issue with using Fuseki as a war file inside jetty. We
have a java application which looks for new data and loads it onto fuseki.
When it is doing it for the first time, it has to create a new index, so we
call the tdb2.tdbloader class directly with appropriate parameters. Here is
the relevant code snippet
import tdb2.tdbloader;
...
public static List<String> TDBLoaderParams = Arrays.asList("-q",
> "--loader", "parallel", "--loc");
> ...
> List<String> tdbParams = new ArrayList<>(TDBLoaderParams);
> tdbParams.add(dstPath);
> tdbParams.addAll(srcPaths);
> try {
> ...
> tdbloader.main(tdbParams.toArray(new String[tdbParams.size()]));
> }
> ...
> ...
>
This works as expected and create a new index at the desired location. Now,
the problem is the same java process has to apply other feeds onto the same
graph, so we move the softlink pointing to the fuseki database and execute
a jetty restart command by calling a shell action using Java ProcessBuilder
process.
The jetty though fails to restart with the following error:
>
> org.apache.jena.assembler.exceptions.AssemblerException: caught: Failed to
> get a lock: file='/home/amit/fuseki/databases/201905302214/tdb.lock':
> held by process 35918 at
> org.apache.jena.assembler.assemblers.AssemblerGroup$PlainAssemblerGroup.openBySpecificType(AssemblerGroup.java:165)
> at
> org.apache.jena.assembler.assemblers.AssemblerGroup$PlainAssemblerGroup.open(AssemblerGroup.java:144)
> at
> org.apache.jena.assembler.assemblers.AssemblerGroup$ExpandingAssemblerGroup.open(AssemblerGroup.java:93)
> at
> org.apache.jena.assembler.assemblers.AssemblerBase.open(AssemblerBase.java:39)
> at
> org.apache.jena.assembler.assemblers.AssemblerBase.open(AssemblerBase.java:35)
> at
> org.apache.jena.fuseki.build.FusekiConfig.getDataset(FusekiConfig.java:353)
> at
> org.apache.jena.fuseki.build.FusekiConfig.buildDataService(FusekiConfig.java:303)
> at
> org.apache.jena.fuseki.build.FusekiConfig.buildDataAccessPoint(FusekiConfig.java:292)
> at
> org.apache.jena.fuseki.build.FusekiConfig.readConfiguration(FusekiConfig.java:275)
> at
> org.apache.jena.fuseki.build.FusekiConfig.readConfigurationDirectory(FusekiConfig.java:254)
> ... ... Caused by: org.apache.jena.dboe.DBOpEnvException: Failed to get a
> lock: file='/home/amit/fuseki/databases/201905302214/tdb.lock': held by
> process 35918 at
> org.apache.jena.dboe.base.file.ProcessFileLock.lockOperation(ProcessFileLock.java:199)
> at
> org.apache.jena.dboe.base.file.ProcessFileLock.lockEx(ProcessFileLock.java:125)
> at
> org.apache.jena.tdb2.sys.DatabaseConnection.buildForCache(DatabaseConnection.java:88)
> at
> org.apache.jena.tdb2.sys.DatabaseConnection.lambda$make$0(DatabaseConnection.java:76)
> at
> java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1660)
>
So the Jetty Server fails to restart while the jvm that created the index
is still active, even though it has completed the index building part. It
restarts fine once the loader JVM dies. It looks like the parallel loader
class is not releasing the lock() properly. FYI, I'm using 3.11 Jena
>From apache jena github
https://github.com/apache/jena/blob/66d14eda44dd0f37a9df31ed27c55c26600ff5f8/jena-db/jena-dboe-base/src/main/java/org/apache/jena/dboe/base/file/ProcessFileLock.java#L184-L218
Regards
Amit Kumar
