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Posted to issues@activemq.apache.org by "William Crowell (JIRA)" <ji...@apache.org> on 2016/09/23 17:25:20 UTC
[jira] [Comment Edited] (AMQ-6441) Incorrect File System Size
Reported with Amazon Elastic File System (EFS)
[ https://issues.apache.org/jira/browse/AMQ-6441?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15517036#comment-15517036 ]
William Crowell edited comment on AMQ-6441 at 9/23/16 5:25 PM:
---------------------------------------------------------------
I have a theory that a long is not large enough to represent 8,796,093,022,208 megabytes, and we are running into an overflow issue.
Given that a long primitive type in Java 7 has a range of -2 to the 63rd power and a maximum value of 2 to the 63rd power -1.
This means that a long can have values -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.
If I convert 8796093022208 megabytes into bytes then that value is 9,223,372,036,854,780,000 which is 4,193 outside the maximum value of a long.
If you happen to be running Java 8, then a unsigned 64-bit long can have a maximum value of 18,446,744,073,709,500,000 which would be large enough.
This means that the call to Java's java.io.File.getTotalSpace() would overflow since it returns a long: https://docs.oracle.com/javase/7/docs/api/java/io/File.html#getTotalSpace()
In Java 8, this probably works fine. Could I propose changing the variable on line 2050 of org.apache.activemq.broker.BrokerService to a double instead of a long?
...
double totalSpace = dir.getTotalSpace();
...
From the link: https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html
"The double data type is a double-precision 64-bit IEEE 754 floating point."
was (Author: william.crowell):
I have a theory that a long is not large enough to represent 8,796,093,022,208 megabytes, and we are running into an overflow issue.
Given that a long primitive type in Java 7 has a range of -2 to the 63rd power and a maximum value of 2 to the 63rd power -1.
This means that a long can have values -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.
If I convert 8796093022208 megabytes into bytes then that value is 9,223,372,036,854,780,000 which is 4,193 outside the maximum value of a long.
If you happen to be running Java 8, then a unsigned 64-bit long can have a maximum value of 18,446,744,073,709,500,000.
This means that the call to Java's java.io.File.getTotalSpace() would overflow since it returns a long: https://docs.oracle.com/javase/7/docs/api/java/io/File.html#getTotalSpace()
In Java 8, this probably works fine. Could I propose changing the variable on line 2050 of org.apache.activemq.broker.BrokerService to a double instead of a long?
...
double totalSpace = dir.getTotalSpace();
...
From the link: https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html
"The double data type is a double-precision 64-bit IEEE 754 floating point."
> Incorrect File System Size Reported with Amazon Elastic File System (EFS)
> -------------------------------------------------------------------------
>
> Key: AMQ-6441
> URL: https://issues.apache.org/jira/browse/AMQ-6441
> Project: ActiveMQ
> Issue Type: Bug
> Affects Versions: 5.11.1
> Reporter: Ismail Bhana
>
> I've set up Active MQ in production with a shared file system master/slave configuration (KahaDB). I've set everything up and mounted the EFS on both EC2 instances.
> When I check the disk free stats I get 8 exabytes for the shared file system:
> {code}
> $ df -h
> eu-west-1a.***.efs.eu-west-1.amazonaws.com:/ 8.0E 0 8.0E 0% /mnt/efs
> {code}
> Unfortunately, ActiveMQ cannot interpret this number (8 exabytes). This may be due to integer truncation.
> Here is a snippet of the log:
> {code}
> Store limit is 102400 mb (current store usage is 0 mb). The data directory: /mnt/efs/kahadb only has -8796093022208 mb of usable space - resetting to maximum available disk space: -8796093022207 mb
> Store limit is -8796093022207 mb, whilst the max journal file size for the store is: 32 mb, the store will not accept any data when used.
> {code}
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