Hi Brett,
SequenceUpdater.clean() is the only method which raises that error. The
header comment on that method says that the condition can arise if
someone else is doing DDL while you are allocating sequence numbers, or
if someone else is scanning SYS.SYSSEQUENCES, or if the database shuts
down while sequence numbers are still being grabbed. Is your application
doing any of this at steady-state?
Thanks,
-Rick
On 9/19/17 3:04 PM, Bergquist, Brett wrote:
I have a simple application that is running with no other access to
the database. A sequence is defined
CREATE SEQUENCE LOG_ENTRY_SEQUENCE AS BIGINT START WITH 1 MINVALUE 1 CYCLE
The application is retrieving the next sequence number with a “VALUES
(NEXT VALUE FOR LOG_ENTRY_SEQUENCE)” statement and then that sequence
number is being used as an ID for the rows to be inserted int another
database table.
500,000 rows are going to be inserted. When this is run, periodically
there is an error being logged by derby.
Here is the derby.log
Tue Sep 19 15:55:06 EDT 2017:
Booting Derby version The Apache Software Foundation - Apache Derby -
10.13.1.1
- (1765088): instance a816c00e-015e-9bb4-c83b-ffffb4d52705
on database directory
/opt/csemlogger/glassfish4/databases/csemloggerdb with class loader
sun.misc.Launcher$AppClassLoader@5c647e05
Loaded from file:/opt/csemlogger/glassfish4/javadb/lib/derby.jar
java.vendor=Oracle Corporation
java.runtime.version=1.8.0_40-b26
user.dir=/
os.name=SunOS
os.arch=amd64
os.version=5.10
derby.system.home=/opt/csemlogger/glassfish4/databases
Database Class Loader started - derby.database.classpath=''
Database Class Loader started - derby.database.classpath='CSEM.csemderby'
Derby could not obtain the locks needed to release the unused,
preallocated values for the sequence 'CSEM'.'LOG_ENTRY_SEQUENCE'. As
a result, unexpected gaps may appear in this sequence.
Derby could not obtain the locks needed to release the unused,
preallocated values for the sequence 'CSEM'.'LOG_ENTRY_SEQUENCE'. As
a result, unexpected gaps may appear in this sequence.
Derby could not obtain the locks needed to release the unused,
preallocated values for the sequence 'CSEM'.'LOG_ENTRY_SEQUENCE'. As
a result, unexpected gaps may appear in this sequence.
Derby could not obtain the locks needed to release the unused,
preallocated values for the sequence 'CSEM'.'LOG_ENTRY_SEQUENCE'. As
a result, unexpected gaps may appear in this sequence.
Here is the code used. Note that it is using JPA, however the
LogEnty entity being inserted is not using the sequence. All
LogEntry ID assignment is done manually using the result of the
sequence number retrieved (the slot assignment).
private static void initializeLoggerEntryTable(SetupContext ctx, long
entryCount) {
EntityManager em = ctx.getEntityManager();
Query nextSeqQuery = em.createNativeQuery("VALUES (NEXT VALUE
FOR LOG_ENTRY_SEQUENCE)");
int j = 0;
// Create a transaction
ctx.getEntityManager().getTransaction().begin();
for (int i = 0; i < entryCount; i++) {
long nextSeq = ((Long)
nextSeqQuery.getSingleResult()).longValue();
long slot = nextSeq % entryCount;
// See if there is a LogEntry at this slot
LogEntry logEntry = em.find(LogEntry.class, slot);
if (null == logEntry) {
// There is not, so create one
logEntry = new LogEntry();
logEntry.setSlot(slot);
// Persist the chassis template
em.persist(logEntry);
}
// Commit the transaction
if (++j >= 10) {
em.getTransaction().commit();
em.clear();
em.getTransaction().begin();
j = 0;
}
}
ctx.getEntityManager().getTransaction().commit();
}
The sequence is not used outside of this code and there is no other
access to the database. I don’t understand why some internal lock
could not be obtained.
Any insight will be greatly appreciated.
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