Great. +1 from me.
On Tue, May 27, 2014 at 7:39 PM, David McLaughlin <da...@dmclaughlin.com>wrote: > Pagination would be a no-op to the client because it would be opt-in only, > so it would continue to fetch all the tasks in one request. > > But you raise a good point in that presumably the client is also going to > be blocked for several seconds while executing getTasksStatus for large > jobs. Making the response more lightweight could be a big win there, but I > would need a better understanding of how the client is using those > responses first. > > > On Tue, May 27, 2014 at 3:34 PM, Mark Chu-Carroll <mchucarr...@apache.org > >wrote: > > > Interestingly, when we first expanded getTasksStatus, I didn't like the > > idea, because I thought it would have exactly this problem! It's a *lot* > of > > information to get in a single burst. > > > > Have you checked what effect it'll have on the command-line client? In > > general, the command-line has the context do a single API call, gathers > the > > results, and returns to a command implementation. It'll definitely > > complicate things to add pagination. How much of an effect will it be? > > > > -Mark > > > > > > > > On Tue, May 27, 2014 at 5:32 PM, David McLaughlin <da...@dmclaughlin.com > > >wrote: > > > > > As outlined in AURORA-458, using the new jobs page with a large (but > > > reasonable) number of active and complete tasks can take a long time[1] > > to > > > render. Performance profiling done as part of AURORA-471 shows that the > > > main factor in response time is rendering and returning the size of the > > > uncompressed payload to the client. > > > > > > To that end, I think we have two approaches: > > > > > > 1) Add pagination to the getTasksStatus call. > > > 2) Make the getTasksStatus response more lightweight. > > > > > > > > > Pagination > > > --------------- > > > > > > Pagination would be the simplest approach, and would scale to > arbitrarily > > > large numbers of tasks moving forward. The main issue with this is that > > we > > > need all active tasks to build the configuration summary at the top of > > the > > > job page. > > > > > > As a workaround we could add a new API call - getTaskConfigSummary - > > which > > > returns something like: > > > > > > > > > struct ConfigGroup { > > > 1: TaskConfig config > > > 2: set<i32> instanceIds > > > } > > > > > > struct ConfigSummary { > > > 1: JobKey jobKey > > > 2: set<ConfigGroup> groups > > > } > > > > > > > > > To support pagination without breaking the existing API, we could add > > > offset and limit fields to the TaskQuery struct. > > > > > > > > > Make getTasksStatus more lightweight > > > ------------------------------------ > > > > > > getTasksStatus currently returns a list of ScheduledTask instances. The > > > biggest (in terms of payload size) child object of a ScheduledTask is > the > > > TaskConfig struct, which itself contains an ExecutorConfig. > > > > > > I took a sample response from one of our internal production instances > > and > > > it turns out that around 65% of the total response size was for > > > ExecutorConfig objects, and specifically the "cmdline" property of > these. > > > We currently do not use this information anywhere in the UI nor do we > > > inspect it when grouping taskConfigs, and it would be a relatively easy > > win > > > to just drop these from the response. > > > > > > We'd still need this information for the config grouping, so we could > add > > > the response suggested for getTaskConfigSummary as another property and > > > allow the client to reconcile these objects if it needs to: > > > > > > > > > struct TaskStatusResponse { > > > 1: list<LightweightTask> tasks > > > 2: set<ConfigGroup> configSummary > > > } > > > > > > > > > This would significantly reduce the uncompressed payload size while > still > > > containing the same data. > > > > > > However, there is still a potentially significant part of a payload > size > > > remaining: task events (and these *are* currently used in the UI). We > > could > > > solve this by dropping task events from the LightweightTask struct too, > > and > > > fetching them lazily in batches. > > > > > > i.e. an API call like: > > > > > > > > > getTaskEvents(1: JobKey key, 2: set<i32> instanceIds) > > > > > > > > > Could return: > > > > > > > > > struct TaskEventResult { > > > 1: i32 instanceId > > > 2: list<TaskEvent> taskEvents > > > } > > > > > > struct TaskEventResponse { > > > 1: JobKey key > > > 2: list<TaskEventResult> results > > > } > > > > > > > > > Events could then only be fetched and rendered as the user clicks > through > > > the pages of tasks. > > > > > > > > > Proposal > > > ------------- > > > > > > I think pagination makes more sense here. It adds moderate overhead to > > the > > > complexity of the UI (this is purely due to our use of smart-table > which > > is > > > not so server-side pagination friendly) but the client logic would > > actually > > > be simpler with the new getTaskConfigSummary api call. > > > > > > I do think there is value in considering whether the ScheduledTask > struct > > > needs to contain all of the information it does - but this could be > done > > as > > > part of a separate or complimentary performance improvement ticket. > > > > > > > > > > > > > > > [1] - At Twitter we observed 2000 active + 100 finished tasks having a > > > payload size of 10MB which took 8~10 seconds to complete. > > > > > >