Hello Paul , Thanks you for your response with some interesting information(files in /tmp).
For my side all other command line work normally(start|stop|status...|) but no restart(this option not recognized). I tried to search the code source and I found that the restart command is not implemented . then I wonder why the documentation does not match the source code ?. Thanks .Teddy On Sat, Jan 12, 2019, 02:39 Paul Rogers <[email protected] wrote: > Let's try to troubleshoot. Does the combination of stop and start work? If > so, then there could be a bug with the restart command itself. > > If neither start nor stop work, it could be that you are missing the > application ID file created when you first started DoY. Some background. > > When we submit an app to YARN, YARN gives us an app ID. We need this in > order to track down the app master for DoY so we can send it commands later. > > When the command line tool starts DoY, it writes the YARN app ID to a > file. Can't remember the details, but it is probably in the $DRILL_SITE > directory. The contents are, as I recall, a long hexadecimal string. > > When you invoke the command line, the tool reads this file to figure to > track down the DoY app master. The tool then sends commands to the app > master: in this case, a request to shut down. Then, for reset, the tool > will communicate with YARN to start a new instance. > > The tool is suppose to give detailed error messages. Did you get any? That > might tell us which of these steps failed. > > Can you connect to the DoY Web UI at the URL provided when you started > DoY? If you can, this means that the DoY App Master is up and running. > > Are you running the client from the same node on which you started it? > That file I mentioned is local to the "DoY client" machine; it is not in > DFS. > > Then, there is one more very obscure bug you can check. On some > distributions, the YARN task files are written to the /tmp directory. Some > Linux systems remove these files from time to time. Once the files are > gone, YARN can no longer control its containers: it won't be able to stop > the app master or the Drillbit containers. There are two fixes. First, go > kill all the processes by hand. Then, move the YARN state files out of > /tmp, or exclude YARN's files from the periodic cleanup. > > Try some of the above and let us know what you find. > > Also, perhaps Abhishek can offer some suggestions as he tested the heck > out of the feature and may have additional suggestions. > > Thanks, > - Paul > > > > On Friday, January 11, 2019, 7:46:55 AM PST, Kwizera hugues Teddy < > [email protected]> wrote: > > hello, > > 2 weeks ago, I began to discover DoY. Today by reading drill documents ( > https://drill.apache.org/docs/appendix-a-release-note-issues/ ) I saw that > we can restart drill cluster by : > > $DRILL_HOME/bin/drill-on-yarn.sh --site $DRILL_SITE restart > > But doesn't work when I tested it. > > No idea about it? > > Thanks. > > > > > On Wed, Jan 2, 2019 at 3:18 AM Paul Rogers <[email protected]> > wrote: > > > Hi Charles, > > > > Your engineers have identified a common need, but one which is very > > difficult to satisfy. > > > > TL;DR: DoY gets as close to the requirements as possible within the > > constraints of YARN and Drill. But, future projects could do more. > > > > Your engineers want resource segregation among tenants: multi-tenancy. > > This is very difficult to achieve at the application level. Consider > Drill. > > It would need some way to identify users to know which tenant they belong > > to. Then, Drill would need a way to enqueue users whose queries would > > exceed the memory or CPU limit for that tenant. Plus, Drill would have to > > be able to limit memory and CPU for each query. Much work has been done > to > > limit memory, but CPU is very difficult. Mature products such as Teradata > > can do this, but Teradata has 40 years of effort behind it. > > > > Since it is hard to build multi-tenancy in at the app level (not > > impossible, just very, very hard), the thought is to apply it at the > > cluster level. This is done in YARN via limiting the resources available > to > > processes (typically map/reduce) and to limit the number of running > > processes. Works for M/R because each map task uses disk to shuffle > results > > to a reduce task, so map and reduce tasks can run asynchronously. > > > > For tools such as Drill, which do in-memory processing (really, > > across-the-network exchanges), both the sender and receiver have to run > > concurrently. This is much harder to schedule than async m/r tasks: it > > means that the entire Drill cluster (of whatever size) be up and running > to > > run a query. > > > > The start-up time for Drill is far, far longer than a query. So, it is > not > > feasible to use YARN to launch a Drill cluster for each query the way you > > would do with Spark. Instead, under YARN, Drill is a long running service > > that handles many queries. > > > > Obviously, this is not ideal: I'm sure your engineers want to use a > > tenant's resources for Drill when running queries, else for Spark, Hive, > or > > maybe TensorFlow. If Drill has to be long-running, I'm sure they's like > to > > slosh resources between tenants as is done in YARN. As noted above, this > is > > a hard problem that DoY did not attempt to solve. > > > > One might suggest that Drill grab resources from YARN when Tenant A wants > > to run a query, and release them when that tenant is done, grabbing new > > resources when Tenant B wants to run. Impala tried this with Llama and > > found it did not work. (This is why DoY is quite a bit simpler; no reason > > to rerun a failed experiment.) > > > > Some folks are looking to Kubernetes (K8s) as a solution. But, that just > > replaces YARN with K8s: Drill is still a long-running process. > > > > To solve the problem you identify, you'll need either: > > > > * A bunch of work in Drill to build multi-tenancy into Drill, or > > * A cloud-like solution in which each tenant spins up a Drill cluster > > within its budget, spinning it down, or resizing it, to stay with an > > overall budget. > > > > The second option can be achieved under YARN with DoY, assuming that DoY > > added support for graceful shutdown (or the cluster is reduced in size > only > > when no queries are active.) Longer-term, a more modern solution would be > > Drill-on-Kubernetes (DoK?) which Abhishek started on. > > > > Engineering is the art of compromise. The question for your engineers is > > how to achieve the best result given the limitations of the software > > available today. At the same time, helping the Drill community improve > the > > solutions over time. > > > > Thanks, > > - Paul > > > > > > > > On Sunday, December 30, 2018, 9:38:04 PM PST, Charles Givre < > > [email protected]> wrote: > > > > Hi Paul, > > Here’s what our engineers said: > > > > From Paul’s response, I understand that there is a slight confusion > around > > how multi-tenancy has been enabled in our data lake. > > > > Some more details on this – > > > > Drill already has the concept of multitenancy where we can have multiple > > drill clusters running on the same data lake enabled through different > > ports and zookeeper. But, all of this is launched through the same hard > > coded yarn queue that we provide as a config parameter. > > > > In our data lake, each tenant has a certain amount of compute capacity > > allotted to them which they can use for their project work. This is > > provisioned through individual YARN queues for each tenant (resource > > caging). This restricts the tenants from using cluster resources beyond a > > certain limit and not impacting other tenants at the same time. > > > > Access to these YARN queues is provisioned through ACL memberships. > > > > —— > > > > Does this make sense? Is this possible to get Drill to work in this > > manner, or should we look into opening up JIRAs and working on new > > capabilities? > > > > > > > > > On Dec 17, 2018, at 21:59, Paul Rogers <[email protected]> > > wrote: > > > > > > Hi Kwizera, > > > I hope my answer to Charles gave you the information you need. If not, > > please check out the DoY documentation or ask follow-up questions. > > > Key thing to remember: Drill is a long-running YARN service; queries DO > > NOT go through YARN queues, they go through Drill directly. > > > > > > Thanks, > > > - Paul > > > > > > > > > > > > On Monday, December 17, 2018, 11:01:04 AM PST, Kwizera hugues Teddy > < > > [email protected]> wrote: > > > > > > Hello, > > > Same questions , > > > I would like to know how drill deal with this yarn fonctionality? > > > Cheers. > > > > > > On Mon, Dec 17, 2018, 17:53 Charles Givre <[email protected] wrote: > > > > > >> Hello all, > > >> We are trying to set up a Drill cluster on our corporate data lake. > Our > > >> cluster requires dynamic YARN queue allocation for multi-tenant > > >> environment. Is this something that Drill supports or is there a > > >> workaround? > > >> Thanks! > > >> —C > >
