Hi Eliot, One nice thing about the MarkLogic documentation for functions is that you can add helpful comments yourself. I've seen others write "See also" comments and have done so myself from time to time. In general I've found the comments very helpful, even if it's a user getting their newbie question answered.
Evan Evan Lenz President, Lenz Consulting Group, Inc. http://lenzconsulting.com On Mon, Aug 14, 2017 at 9:57 AM, Erik Hennum <[email protected]> wrote: > Hi, Eliot and Ron: > > The return option is explained with the rest of the options in the eval > article: > > http://docs.marklogic.com/xdmp:eval > > The second example under spawn uses the promise: > > http://docs.marklogic.com/xdmp:spawn > > As Ron notes, the server field is only useful if the polling requests go > back to the same host. > > To allow for restarts, the polling logic should check for the persisted > final status document if the server field is empty. (That's the > motivation for persisting a final status document even when using server > fields.) > > Thanks for the feedback on the documentation -- I'll pass that along. > > > Erik Hennum > > ------------------------------ > *From:* [email protected] [ > [email protected]] on behalf of Ron Hitchens [ > [email protected]] > *Sent:* Monday, August 14, 2017 7:55 AM > *To:* MarkLogic Developer Discussion > *Subject:* Re: [MarkLogic Dev General] Tracking Spawned Tasks? > > > Proceed with caution when using server fields. They exist only on a > single machine, they are not propagated across nodes in a cluster. If you > have a cluster behind a load balancer (as most are) and you stash something > in a server field to be checked later, the next request may be vectored to > a different cluster node, where your stashed value will not be present. > Likewise, if you put something in a field to be picked up by a spawned > task, the spawned task may run on a different node. > > ---- > Ron Hitchens [email protected], +44 7879 358212 <+44%207879%20358212> > > > On August 14, 2017 at 3:24:32 PM, Eliot Kimber ([email protected]) > wrote: > > I like using set-server-field: my requirement feels like just what server > fields were intended for. > > Cheers, > > E. > -- > Eliot Kimber > http://contrext.com > > > > On 8/14/17, 8:32 AM, "[email protected] on behalf > of Erik Hennum" <[email protected] on behalf of > [email protected]> wrote: > > Hi, Eliot: > > xdmp:spawn() doesn't return an identifier because, if it is used as a > future via the result option, it is obligated to return the result. > > The approach you sketch below -- passing in an identifier and writing > tickets to a status database -- is pretty much what InfoStudio did. > > One refinement would be to log status in a server field via > xdmp:set-server-field() and, on completion, write final status to a > database (for durability in the case of a restart). > > > Hoping that helps, > > > Erik Hennum > > ________________________________________ > From: [email protected] [general-bounces@developer. > marklogic.com] on behalf of Eliot Kimber [[email protected]] > Sent: Saturday, August 12, 2017 10:15 AM > To: MarkLogic Developer Discussion > Subject: [MarkLogic Dev General] Tracking Spawned Tasks? > > Using ML 8 > > I’m refining a profiling application that spawns a number of tasks and > then, eventually, reports on the results once all the tasks have completed. > > Right now I just fire off the tasks and then refresh my app, which looks > for results. > > It would be nice to be able to show the status of the spawned tasks but it > looks like xdmp:spawn() doesn’t return anything (sort of expected to get > some sort of task ID or something) and so there’s no obvious way to track > spawned tasks from the spawning application. > > I could do something like generate private task IDs and pass those as > parameters to the spawned tasks and then maintain a set of task status > docs, but I was hoping there was some something easier. > > It seems like it would be a common requirement but I couldn’t find > anything useful in the ML 8 docs or searching the web. > > Thanks, > > Eliot > -- > Eliot Kimber > http://contrext.com > > > > > _______________________________________________ > General mailing list > [email protected] > Manage your subscription at: > http://developer.marklogic.com/mailman/listinfo/general > _______________________________________________ > General mailing list > [email protected] > Manage your subscription at: > http://developer.marklogic.com/mailman/listinfo/general > > > > _______________________________________________ > General mailing list > [email protected] > Manage your subscription at: > http://developer.marklogic.com/mailman/listinfo/general > > > _______________________________________________ > General mailing list > [email protected] > Manage your subscription at: > http://developer.marklogic.com/mailman/listinfo/general > >
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