In the last few days I've suddenly had a bunch of OOM exceptions. I'm
using Derby 10.9.1.0, Oracle Java 1.8.0 on Ubuntu 64-bit, and haven't
upgraded for a while (probably years, looking at those numbers).
The place where they happen is in a call to executeQuery() in a method
which displays a view as a table. Analysing the heap dump for the latest
one with the Eclipse memory analyser shows this:
One instance of "org.apache.derby.impl.store.access.sort.MergeInserter"
loaded by "org.eclipse.jetty.webapp.WebAppClassLoader @ 0xf04231b0"
occupies 134,841,800 (64.65%) bytes. The memory is accumulated in one
instance of "org.apache.derby.impl.store.access.sort.SortBuffer", loaded
by "org.eclipse.jetty.webapp.WebAppClassLoader @ 0xf04231b0", which
occupies 134,841,496 (64.65%) bytes.
One instance of "org.apache.derby.impl.services.cache.ConcurrentCache"
loaded by "org.eclipse.jetty.webapp.WebAppClassLoader @ 0xf04231b0"
occupies 43,766,832 (20.98%) bytes. The memory is accumulated in one
instance of "org.apache.derby.impl.services.cache.ConcurrentCache",
loaded by "org.eclipse.jetty.webapp.WebAppClassLoader @ 0xf04231b0",
which occupies 43,766,832 (20.98%) bytes.
The query itself was:
SELECT DateTimeFormat(t_time,null) AS t_time,
facility,event,details,name,username,sector,item
FROM system_log_view
ORDER BY time DESC
NULLS LAST
FETCH NEXT 20 ROWS ONLY
The view is nothing special except that t_time is a duplicate of the
time column (the timestamp of the log entry) used to create a separate
formatted copy for display purposes:
CREATE VIEW system_log_view AS
SELECT time AS t_time,
facility,
event,
details,
name,
username,
sector,
item,
time
FROM system_log;
The stack trace shows the error is occurring inside the call to
DateTimeFormat, which is again nothing special:
public static final String formatDateTime (Timestamp date, String
locale) {
if (date == null) {
return null;
}
else {
String fmt = translate("d-MMM-yyyy 'at' HH:mm",locale);
return translatePhrases(fmt.format(date),locale);
}
}
Here's the start of the stack trace:
java.sql.SQLException: The exception 'java.lang.OutOfMemoryError: GC
overhead limit exceeded' was thrown while evaluating an expression.
at java.text.DigitList.clone()Ljava/lang/Object; (DigitList.java:736)
at java.text.DecimalFormat.clone()Ljava/lang/Object;
(DecimalFormat.java:2711)
at java.text.SimpleDateFormat.initialize(Ljava/util/Locale;)V
(SimpleDateFormat.java:645)
at
java.text.SimpleDateFormat.<init>(Ljava/lang/String;Ljava/util/Locale;)V
(SimpleDateFormat.java:605)
at java.text.SimpleDateFormat.<init>(Ljava/lang/String;)V
(SimpleDateFormat.java:580)
at
database.Functions.formatDateTime(Ljava/sql/Timestamp;Ljava/lang/String;)Ljava/lang/String;
(Functions.java:51)
Does anyone have any idea what might be happening, or what I can do to
find out more?
TIA,
--
John English
