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10-17-2018
02:28 PM
yes, that makes sense. When you start the DistirbutedMapCache server is starts a server on each NiFi node. The DIstributedMapCache Client should be configured to point at one specific node, so that every node pulls cache entries from same server. - A little back history: The DistibrutedMapCacheServer and DistirbutedMapCacheClient controller services date back to original NiFi releases versions. Back in those days there was no zero master clustering which we have now. There was a dedicated server that ran a NiFi Cluster Manager (NCM). At that time the DistributedMapCacheServer could only be setup on the NCM. - Once NiFi moved away from having a NCM, the functionality of these controller services was not changed to avoid breaking flows of user who moved to latest versions. The DistirbutedMapCacheServer does not offer HA (if node hosting server goes down, cache becomes unavailable). To provide HA here, new external HA caches options have been added as options. - thanks, Matt
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10-17-2018
12:31 PM
@pavan srikar I should add that there is no processor that will specifically clone a FlowFile to every node in the NiFi cluster. - But there are other options if you do not want to standup an external map cache server. - Perhaps setting up a disk mount that is shared across all nodes. On Primary node only you run a flow that retrieves a new token every ~55 minutes writes it to this shared mounted directory set to overwrite previous written token each time. Then on all nodes you could create a flow that consumes this token without deleting it on schedule to perform your all node tasks. - Just a second option for you. - Thank you, Matt
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10-17-2018
12:23 PM
1 Kudo
@pavan srikar - The design you have in place looks to be correct solution based on your described use case here. Every node in your cluster runs the exact same flow.xml.gz - You would typically configure your "PutDistributedMapCache" and "FetchDistributedMapCache" processors to use a "Distributed Cache Service" that every node has access to. - This allows you run a single "primary node" only flow that retrieves the token based on a one hour cron and writes it to the distributed Map cache and then have a second flow that every node runs that pulls that stored token value from the distributed map cache and uses it for your downstream calls. - Using the "RedisDistributedMapCacheClientService" controller service for example allows you to set a TTL on the values you store in the cache. This allows you to expire the stored token before it is no longer valid. For example token is good for 1 hour, so you could set TTL to 50 - 55 minutes. - Thank you, Matt - If you found this answer addressed your question, please take a moment to login in and click the "ACCEPT" link.
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10-09-2018
02:09 PM
1 Kudo
@Cooper Max NiFi has two processes as you see above that are running. The NiFi bootstrap process is what is kicked off when starting NiFi and it then spans off the main NiFi process. The bootstrap process then monitors for the pid of that main process and if it disappears, the output you see above is thrown and the bootstrap then attempts tp restart the main process. - If your nifi-app.log is not exhibiting any signs of issues going on in your dataflow leading up to this event, the killing of this NiFi process is being triggered external to NiFi. - Most commonly you may find that the server itself has killed the process. I would suggest looking at your server logs for the execution of "OOM killer". When memory resources on a server reach usage a level where the OS feels it could result in the server become unresponsive or crash, oom killer is launched which evaluates the running process and elects a process to be killed to free memory to protect the OS. Considering the memory footprint of a typical main NiFi JVM process, it is commonly selected by the oom killer. - To resolve this issue, you would need to reduce the amount of memory that is being consumed by running process on this same server. - Do not run NIFi on server where other service are co-located - Reduce the configured JVM setting for the NiFi process in the nifi-bootsrap.conf file. ----- Above may require you to re-evaluate your dataflow design(s) in NiFi to reduce heap memory usage. - Thank you, Matt - If you found this answer addressed your question, please take a moment to login in and click the "ACCEPT" link.
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10-09-2018
01:03 PM
1 Kudo
@Abdou B. - "Stopped" is probably not the correct word to use here. A processor that is started then executes based on the configured "run schedule". When Back pressure is being applied to a processor by one of the processors outgoing connections, the processor will no longer be scheduled to run. It is still started. As soon as back pressure is no longer being applied, the processor will begin executing again based on run schedule. - Thanks, Matt
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10-04-2018
02:03 PM
FlowFile content is not stored in provenance repository. The ability to view or replay content will only work if content still exists in content repository. Content repository can be configured to retain archived content. But keep in mind that the content of active FlowFiles still in dataflows will always take priority over archived content. If active data triggers thresholds for disk usage to exceed configured values, all archived content will be purged. Thanks, Matt - If you found this answer addressed your question, please take a moment to login in and click the "ACCEPT" link.
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10-02-2018
12:36 PM
2 Kudos
@Thomas Lebrun Provenance events are dated. While the provenance repository can be moved from one NiFi to another without issue, simply backing up a portion of it or all of it and trying to merge it with an existing provenance repository later is not possible. - Even trying to take an entire backed up provenance repository and placing it in a clean NiFi later would have its challenges. You would need to make sure the provenance retention settings in whatever NiFi you placed this backed up Provenance repository extended beyond the age of the oldest event in that backed up provenance repository or NiFi would simply purge all the events on startup. - A better option might be to consider building a dataflow on each of your NiFi instances/clusters that uses the SiteToSiteProvenanceReportingTask to send provenance events to another NiFi where it would have a dataflow build to wrote out those events to your choice of long term storage or auditing endpoint of your choice. The provenance events output by this reporting task are just JSON. - https://nifi.apache.org/docs/nifi-docs/components/org.apache.nifi/nifi-site-to-site-reporting-nar/1.7.1/org.apache.nifi.reporting.SiteToSiteProvenanceReportingTask/index.html - Thank you, Matt
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10-01-2018
05:52 PM
@yazeed salem Your NiFi expression Language statement looks good. I even tested base on your example and it routed my flowfiles correctly Make sure that each of the FlowFiles being processed have required FlowFile Attributes set on them. You can stop your RouteOnAttribute processor and allow a few files to queue in the connection feeding it. Then right click on connection and select "List queue". You can then click on "details" icon to far left of any FlowFIle to verify that it does have correct attributes set on it. - - Thank you, Matt - If you found this answer addressed your question, please take a moment to login in and click the "ACCEPT" link.
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09-14-2018
01:47 PM
@sri chaturvedi yes, potentially if there are enough inbound FlowFiles to trigger processor to run 4 times concurrently.
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09-12-2018
12:53 PM
2 Kudos
@sri chaturvedi - You are only going to benefit from setting run duration to 50ms if the processing of each incoming FlowFile to the putSQL processor is taking fractions of the 50ms duration. Details on "Run duration" and how it works can be found here: https://community.hortonworks.com/articles/221807/understanding-nifi-processors-run-duration-functio.html --------- When you set a run duration on a lot of processors, when those threads are executed, they will consume that CPU thread for possibly longer then needed. This means that other processors may end up waiting longer for a thread. - Consider this example: Your putSQL happens to be taking 10 ms to execute the put of a FlowFile. That means that with a 50 ms run duration it would put 5 FlowFiles within the single thread execution. What happens if incoming connection queue only has 1 FlowFile at time of execution? The processor holds that thread for 40 ms longer then needed. That is 40 ms of cpu time not available to another processor. - Since there is some time overhead in staring and stopping threads, run duration is very useful when you have a high sustained dataflow. It can actually decrease performance when used in dataflow where there is not high volume of FlowFiles (High volume is relative to the processors designed task.) - ---------- When it comes to concurrent tasks, this dictates parallel processor execution. - Since your canvas has 2000 processors, you need to understand that all these processor cannot execute at the exact same time. There is only so much CPU available and NiFi has a configureable thread pool size. This means that many processors may be just waiting in line for their chance to to get time on the CPU. - Details on processor Concurrent task setting recommendations can be found here: https://community.hortonworks.com/articles/221808/understanding-nifi-max-thread-pools-and-processor.html - ----------- - You also mentioned NiFi UI slowness. It may be related to nothing above: https://community.hortonworks.com/articles/184786/hdfnifi-improving-the-performance-of-your-ui.html - Thank you, Matt - If you found this answer addressed your question, please take a moment to login in and click the "ACCEPT" link.
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