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From "Alan Burlison (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HADOOP-12488) DomainSocket: Solaris does not support timeouts on AF_UNIX sockets
Date Mon, 23 Nov 2015 11:54:11 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-12488?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Alan Burlison updated HADOOP-12488:
-----------------------------------
    Attachment: HADOOP-12488.001.patch

> DomainSocket: Solaris does not support timeouts on AF_UNIX sockets
> ------------------------------------------------------------------
>
>                 Key: HADOOP-12488
>                 URL: https://issues.apache.org/jira/browse/HADOOP-12488
>             Project: Hadoop Common
>          Issue Type: Sub-task
>          Components: net
>    Affects Versions: 2.7.1
>         Environment: Solaris
>            Reporter: Alan Burlison
>            Assignee: Alan Burlison
>         Attachments: HADOOP-12488.001.patch
>
>
> From the hadoop-common-dev mailing list:
> http://mail-archives.apache.org/mod_mbox/hadoop-common-dev/201509.mbox/%3C560B99F6.6010408@oracle.com%3E
> http://mail-archives.apache.org/mod_mbox/hadoop-common-dev/201510.mbox/%3C560EA6BF.2070001@oracle.com%3E
> {quote}
> Now that the Hadoop native code builds on Solaris I've been chipping 
> away at all the test failures. About 50% of the failures involve 
> DomainSocket, either directly or indirectly. That seems to be mainly 
> because the tests use DomainSocket to do single-node testing, whereas in 
> production it seems that DomainSocket is less commonly used 
> (https://hadoop.apache.org/docs/r2.7.1/hadoop-project-dist/hadoop-hdfs/ShortCircuitLocalReads.html).
> The particular problem on Solaris is that socket read/write timeouts 
> (the SO_SNDTIMEO and SO_RCVTIMEO socket options) are not supported for 
> UNIX domain (PF_UNIX) sockets. Those options are however supported for 
> PF_INET sockets. That's because the socket implementation on Solaris is 
> split roughly into two parts, for inet sockets and for STREAMS sockets, 
> and the STREAMS implementation lacks support for SO_SNDTIMEO and 
> SO_RCVTIMEO. As an aside, performance of sockets that use loopback or 
> the host's own IP is slightly better than that of UNIX domain sockets on 
> Solaris.
> I'm investigating getting timeouts supported for PF_UNIX sockets added 
> to Solaris, but in the meantime I'm also looking how this might be 
> worked around in Hadoop. One way would be to implement timeouts by 
> wrapping all the read/write/send/recv etc calls in DomainSocket.c with 
> either poll() or select().
> The basic idea is to add two new fields to DomainSocket.c to hold the 
> read/write timeouts. On platforms that support SO_SNDTIMEO and 
> SO_RCVTIMEO these would be unused as setsockopt() would be used to set 
> the socket timeouts. On platforms such as Solaris the JNI code would use 
> the values to implement the timeouts appropriately.
> To prevent the code in DomainSocket.c becoming a #ifdef hairball, the 
> current socket IO function calls such as accept(), send(), read() etc 
> would be replaced with a macros such as HD_ACCEPT. On platforms that 
> provide timeouts these would just expand to the normal socket functions, 
> on platforms that don't support timeouts it would expand to wrappers 
> that implements timeouts for them.
> The only caveats are that all code that does anything to a PF_UNIX 
> socket would *always* have to do so via DomainSocket. As far as I can 
> tell that's not an issue, but it would have to be borne in mind if any 
> changes were made in this area.
> Before I set about doing this, does the approach seem reasonable?
> {quote}
> {quote}
> Unfortunately it's not a simple as I'd hoped. For some reason I don't 
> really understand, nearly all the JNI methods are declared as static and 
> therefore don't get a "this" pointer and as a consequence all the class 
> data members that are needed by the JNI code have to be passed in as 
> parameters. That also means it's not possible to store the timeouts in 
> the DomainSocket fields from within the JNI code. Most of the JNI 
> methods should be instance methods rather than static ones, but making 
> that change would require some significant surgery to DomainSocket.
> {quote}



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