4f3a11b4db
A bunch of fixes from the /tmp/iof-fixes branch that fix up ''some'' (but not ''all'') of the problems that we have seen with iof: * Reading very large files via stdin redirected to orteun (Sun saw this) * Reading a little bit of a large file redirected to orterun's stdin and then either closing stdin or exiting the process The Big Change was to make the proxy iof (the one running in non-HNP orteds) send back a "I'm closing the stream" ACK back to the service iof. This tells the HNP that there will be nothing more coming from that peer, and therefore the iof forward should be removed. Many other minor cleanups/fixes, terminology changes, and documentation additions are included in this commit as well. However, there are still some pretty big outstanding issues with IOF that are not addressed either by #967 or this commit. A few examples: * IOF was designed to allow multiple subscribers to a single stream. We're not entirely sure that this works (for one thing, there is nothing in the ORTE/OMPI code base that uses this functionality). * There are also resources leaked when processes/jobs exit (per Ralph's first comment on this ticket). * There is no feedback to close orterun's stdin when all subscribers to the corresponding stream have closed stdin. This commit was SVN r14967. The following Trac tickets were found above: Ticket 967 --> https://svn.open-mpi.org/trac/ompi/ticket/967
179 строки
8.6 KiB
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179 строки
8.6 KiB
Plaintext
Some notes from Jeff/Rolf while trying to figure out how IOF works...
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1. E-mail from Rolf->Jeff with some pretty ASCII art
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2. Notes from Jeff about problems we'll have when/if we ever try to
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use IOF more creatively.
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===============================================================================
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From: Rolf.Vandevaart@Sun.COM
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Subject: Picture of IOF side of things.
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Date: June 7, 2007 10:43:42 AM EDT
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To: jsquyres@cisco.com
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Not sure if this will come out for you, but here is an ASCII represantation of what
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the HNP looks like after IOF has been wired up.
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VIEW OF DATA STRUCTURES ON IOF SVC SIDE
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KEY: ORTE_IOF_SOURCE=0
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ORTE_IOF_SINK=1
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After the job starts up, this is how things look on the HNP side of things.
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ENDPOINTS (orte_iof_base_endpoint_t)
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mode origin tag fd seq ack src_frags sink_frags notes
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=============================================================================================
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1 0,0,0 1 1 0 0 0 0 pull() call from rmgr<-
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============================================================================================= |
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1 0,0,0 2 2 0 0 0 0 pull() call from rmgr<-|---
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============================================================================================= | |
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0 0,0,0 0 0 0 0 0 0 push() call from rmgr | |
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============================================================================================= | |
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SUBSCRIBERS (orte_iof_svc_sub_t) | |
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ORIGIN TARGET (list) | |
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name mask tag name mask tag endpoint forward has_been_acked last_ack_forwarded | |
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====================================================================================== | |
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0,1,0 2 1 0,0,0 2 1 0 | |
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ptr-------------------------------------------------| |
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====================================================================================== |
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0,1,0 2 2 0,0,0 2 2 0 |
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ptr-----------------------------------------------------|
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======================================================================================
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0,0,0 ff 0 0,1,0 2 0 NULL 1 -----------------------------------
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====================================================================================== |
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PUBLISHED (orte_iof_svc_pub_t) |
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name proxy mask tag endpoint |
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========================================================================================= |
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0,1,0 0,0,1 ff 0 NULL <------------------
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=========================================================================================
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FORWARD (orte_iof_svc_fwd_t)
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This structure is just a connection from a subscriber to publisher. I have
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omitted it in the drawings. However, it is worth pointing out the structure
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as I am not clear on why we have the table.
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struct orte_iof_svc_fwd_t {
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opal_list_item_t super;
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orte_iof_svc_pub_t* fwd_pub;
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opal_hash_table_t fwd_seq_hash;
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};
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Note: This first subscriber says that it will receive from any process
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in the job. Note that the jobid=1 and the mask=2. So, we expect this
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to collect the stdout from any of the ranks. Obviously the second
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subscriber says the same thing but for stderr. The third subscriber
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is for receving data from stdin and sending it out to rank 0 of
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the job. Notice the mask=ff which means compare cellid,jobid,vpid
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when addressing where the data goes.
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The first endpoint is created by a call to pull by the rmgr. After
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the endpoint is created, a subscription is created as well. Then, the
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subscription is tied to the endpoint.
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For the stdin creation, we first create the subscription, and then the
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endpoint. In that way, the endpoint is not found and does not get
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tied to the subscription. Hmmm, this I do not really understand.
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APPENDIX A
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These are the defines that go with the mask.
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#define ORTE_NS_CMP_NONE 0x00
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#define ORTE_NS_CMP_CELLID 0x01
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#define ORTE_NS_CMP_JOBID 0x02
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#define ORTE_NS_CMP_VPID 0x04
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#define ORTE_NS_CMP_ALL 0Xff
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When we get a HDR_MSG, we call orte_iof_svc_proxy_msg()
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APPENDIX B
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There are two dbx files that help get to where we want to get
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for seeing how things work.
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start.x : Run this first to get initial breakpoint. Needs this
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so we can set additional breakpoints. This also has some very
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helpful aliases for looking at the structures shown above.
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follow.x : Run this second to set initial breakpoints and setup
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some useful aliases.
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===============================================================================
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Random notes from Jeff:
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- Many issues may not come up because we only have single subscribers;
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I'm sure new things will come up. Examples:
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- What happens if all subscribers to a stream disconnect, and then a
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new subscriber connects? I'm guessing the ACKs will be all
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screwed up and we'll never end up reading from that fd again
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(because it will likely be stalled because not enough acks have
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been received, and therefore it removed itself from the event
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engine).
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- If all subscribers disconnect from a stdin/SINK, chances are that
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we'll lose the last frag that was sent before the disconnect.
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I.e., if there was a frag in flight when the disconnect was
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received, that frag is effectively lost. So if someone reconnects
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to the stdin stream later, it won't start reading exactly where
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the first subscriber left off. We need to define what is
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*supposed* to happen here...
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- odls default: make handling of vpid 0 uniform between setup and
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takedown -- some kind of global variable, perhaps? (not multi-proc /
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thread safe)
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- odls default: currently, we publish stdin (if relevant), stdout, and
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stderr (note that only the stdin publish message gets sent to svc;
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the publish for SOURCEs stdout/stderr is not actually sent to the
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svc because all SOURCE frags are sent to the svc automatically).
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But we only unpublish stdout. I think we should either:
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- publish stdin, stdout, stderr, and unpublish stdin, stdout, stderr
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or
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- publish stdin, and unpublish stdin
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I.e., make the code symmetric.
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Note, however, that unpublish for STDOUT/STDERR are sent to the svc
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(whereas publish for STDOUT/STDERR are not). So if we unpublish
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stdout/stderr, we'll be creating a storm to the svc upon shutdown
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(i.e,. scalability problems). :-(
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- for scalability, we want to be able to change the proxy to *not*
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unconfitionally send everything to svc. But this has the problem
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that if we do this, then we have to send the publish request to the
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svc (which we don't today since everything just automatically goes
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to svc). But then in the common case (where vpid!=0 has no
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stdout/stderr), we're flooding svc with N publish requests from all
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the vpids, simply creating a different scalability problem (during
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startup).
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- random q: are the proxy publish requests not sent back to svc
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because it prevents a storm of publish requests during startup?
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I.e., this was intentional to give better scalability? Could be;
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but it still seems weird...
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Perhaps a better scheme would be to have the IOF *assume* that the
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stdin/stdout/stderr are all published upon startup (or be told by a
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single control message; perhaps in the app context?) and further
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*assume* that they are all unpublished when the job completes.
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Putting this info in the app context (for example) might jive with a
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more capable orterun that allows flexible stdin/stdout/stderr
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mapping (think: mpirun --screen ...). mpirun makes the decision
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about how to wire up stdin/stdout/stderr and includes it in the app
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context (or whatever). This is given to the svc who then creates
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publications as relevant. Upon job completion, all
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publications/subscriptions related to that job are destroyed.
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