The HarvestMonitor creates a lot of noise from the StartedJobHistoryChartGen

I'm seeing a lot of these in the GUI log:

11:25:31.386 ERROR d.n.h.h.m.StartedJobHistoryChartGen - IOFailure while
copying PNG file
dk.netarkivet.common.exceptions.IOFailure: Error copying file
'/tmp/205055-history8280706966885575649.1440408329414.png' to
'/home/devel/Stresstest/tmpdircommon/History/webapp/205055-history.png'
at
dk.netarkivet.common.utils.FileUtils.copyFile(FileUtils.java:384)
~[common-core-5.0-RC3-SNAPSHOT.jar:9a7fd2178eb21f1de918ca787a3b0f80e5a73197]
at
dk.netarkivet.harvester.harvesting.monitor.StartedJobHistoryChartGen$ChartGen.run(StartedJobHistoryChartGen.java:214)
~[harvester-core-5.0-RC3-SNAPSHOT.jar:9a7fd2178eb21f1de918ca787a3b0f80e5a73197]
at
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
[na:1.8.0_25]
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
[na:1.8.0_25]
at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
[na:1.8.0_25]
at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
[na:1.8.0_25]
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
[na:1.8.0_25]
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
[na:1.8.0_25]
at java.lang.Thread.run(Thread.java:745) [na:1.8.0_25]
Caused by: java.nio.channels.ClosedByInterruptException: null
at
java.nio.channels.spi.AbstractInterruptibleChannel.end(AbstractInterruptibleChannel.java:202)
~[na:1.8.0_25]
at sun.nio.ch.FileChannelImpl.size(FileChannelImpl.java:314)
~[na:1.8.0_25]
at
dk.netarkivet.common.utils.FileUtils.copyFile(FileUtils.java:364)
~[common-core-5.0-RC3-SNAPSHOT.jar:9a7fd2178eb21f1de918ca787a3b0f80e5a73197]
... 8 common frames omitted

And also those history.png files which do make it to the webapp
directory are all null-bytes. Looks like some sort of syncro problem -
the files being copied before they're written, maybe.