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https://issues.apache.org/jira/browse/BROOKLYN-526?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16114192#comment-16114192
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Aled Sage commented on BROOKLYN-526:
------------------------------------
This is surprising because we are supposed to be doing an atomic move of the
file (we write to a temp file, then move it to overwrite the original file -
therefore avoiding the possibility of something reading the file when it is
half written).
Either our code isn't doing this as well as I thought, or the OS guarantees for
such an atomic move are not as strong as I thought!
See {{org.apache.brooklyn.core.mgmt.persist.FileBasedStoreObjectAccessor.put}}
and its call to
{{org.apache.brooklyn.core.mgmt.persist.FileBasedObjectStore.move}}, which then
calls:
{noformat}
java.nio.file.Files.move(srcFile.toPath(), destFile.toPath(),
StandardCopyOption.ATOMIC_MOVE);
{noformat}
On a quick look, I'm not sure how we could improve that code (without making it
a lot more complicated, such as multiple files with version numbers in their
names etc)!
> Laptop crash (?) caused empty files in persisted state
> ------------------------------------------------------
>
> Key: BROOKLYN-526
> URL: https://issues.apache.org/jira/browse/BROOKLYN-526
> Project: Brooklyn
> Issue Type: Bug
> Affects Versions: 0.11.0
> Reporter: Aled Sage
>
> My mac laptop crashed while Brooklyn was running. After restart the mac, and
> restarting Brooklyn, I saw exceptions like that below many times:
> {noformat}
> 2017-08-04 09:23:52,889 WARN 122 o.a.b.c.m.r.RebindExceptionHandlerImpl
> [ooklyn-persister] Rebind: continuing after problem loading memento: memento
> ielugq12x0 loading raw error
> org.apache.brooklyn.util.exceptions.PropagatedRuntimeException:
> SAXParseException: Premature end of file.
> at
> org.apache.brooklyn.util.exceptions.Exceptions.propagate(Exceptions.java:129)[143:org.apache.brooklyn.utils-common:0.12.0.SNAPSHOT]
> at
> org.apache.brooklyn.util.core.xstream.XmlUtil.xpath(XmlUtil.java:78)[122:org.apache.brooklyn.core:0.12.0.SNAPSHOT]
> at
> org.apache.brooklyn.util.core.xstream.XmlUtil.xpathHandlingIllegalChars(XmlUtil.java:100)[122:org.apache.brooklyn.core:0.12.0.SNAPSHOT]
> at
> org.apache.brooklyn.util.core.xstream.XmlUtil.xpathHandlingIllegalChars(XmlUtil.java:87)[122:org.apache.brooklyn.core:0.12.0.SNAPSHOT]
> at
> org.apache.brooklyn.core.mgmt.persist.BrooklynMementoPersisterToObjectStore$2.visit(BrooklynMementoPersisterToObjectStore.java:335)[122:org.apache.brooklyn.core:0.12.0.SNAPSHOT]
> at
> org.apache.brooklyn.core.mgmt.persist.BrooklynMementoPersisterToObjectStore$1VisitorWrapper.run(BrooklynMementoPersisterToObjectStore.java:528)[122:org.apache.brooklyn.core:0.12.0.SNAPSHOT]
> at
> java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)[:1.8.0_144]
> at
> java.util.concurrent.FutureTask.run(FutureTask.java:266)[:1.8.0_144]
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)[:1.8.0_144]
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)[:1.8.0_144]
> at java.lang.Thread.run(Thread.java:748)[:1.8.0_144]
> Caused by: org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1;
> Premature end of file.
> at
> com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:257)[:1.8.0_144]
> at
> com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:339)[:1.8.0_144]
> at
> org.apache.brooklyn.util.core.xstream.XmlUtil.xpath(XmlUtil.java:69)[122:org.apache.brooklyn.core:0.12.0.SNAPSHOT]
> ... 9 more
> {noformat}
> Looking in the persisted state directory, there are a bunch of size-zero
> files (for 34 enrichers, 4 feeds, 6 locations and 2 policies)!
> The timestamps for these zero-size files are the newest in the persistence
> directories.
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