Re: Partitioning and scale
Timothy, Kafka is not designed to support millions of topics. Zookeeper will become a bottleneck, even if you deploy more brokers to get around the # of files issue. In normal cases, it might work just fine with the right sized cluster. However, when there are failures, the time to recovery could be a few minutes instead of a few 100s of ms or few seconds. Also, even if you go with one topic per session id approach, it will be unscalable when the key space increases in the future. A more scalable approach is what Milind described. Use the sticky partitioning feature in 08 and have a session id always get routed to a particular partition. Then each of your consumers can be sure that they will always receive data for a subset of the session ids. So you can do any locality sensitive processing on your consumers for processing user sessions. Thanks, Neha On Thu, May 23, 2013 at 4:36 PM, Milind Parikh milindpar...@gmail.comwrote: Number of files to manage by os, I suppose. Why wouldn't you use consistent hashing with deliberately engineered collisions to generate a limited number of topics / partitions and filter at the consumer level? Regards Milind On May 23, 2013 4:22 PM, Timothy Chen tnac...@gmail.com wrote: Hi Neha, Not sure if this sounds crazy, but if we'd like to have the events for the same session id go to the same partition one way could be that each session key creates its own topic with single partition, therefore there could be millions of topic with single partition. I wonder what would be the bottleneck of doing this? Thanks, Tim On Wed, May 22, 2013 at 4:32 PM, Neha Narkhede neha.narkh...@gmail.com wrote: Not automatically as of today. You have to run the reassign-partitions tool and explicitly move selected partitions to the new brokers. If you use this tool, you can move partitions to the new broker without any downtime. Thanks, Neha On Wed, May 22, 2013 at 2:20 PM, Timothy Chen tnac...@gmail.com wrote: Hi Neha/Chris, Thanks for the reply, so if I set a fixed number of partitions and just add brokers to the broker pool, does it rebalance the load to the new brokers (along with the data)? Tim On Wed, May 22, 2013 at 1:15 PM, Neha Narkhede neha.narkh...@gmail.com wrote: - I see that Kafka server.properties allows one to specify the number of partitions it supports. However, when we want to scale I wonder if we add # of partitions or # of brokers, will the same partitioner start distributing the messages to different partitions? And if it does, how can that same consumer continue to read off the messages of those ids if it was interrupted in the middle? The num.partitions config in server.properties is used only for topics that are auto created (controlled by auto.create.topics.enable). For topics that you create using the admin tool, you can specify the number of partitions that you want. After that, currently there is no way to change that. For that reason, it is a good idea to over partition your topic, which also helps load balance partitions onto the brokers. You are right that if you change the number of partitions later, then previously messages that stuck to a certain partition would now get routed to a different partition, which is undesirable for applications that want to use sticky partitioning. - I'd like to create a consumer per partition, and for each one to subscribe to the changes of that one. How can this be done in kafka? For your use case, it seems like SimpleConsumer might be a better fit. However, it will require you to write code to handle discovery of leader for the partition that your consumer is consuming. Chris has written up a great example that you can follow - https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+SimpleConsumer+Example Thanks, Neha On Wed, May 22, 2013 at 12:37 PM, Chris Curtin curtin.ch...@gmail.com wrote: Hi Tim, On Wed, May 22, 2013 at 3:25 PM, Timothy Chen tnac...@gmail.com wrote: Hi, I'm currently trying to understand how Kafka (0.8) can scale with our usage pattern and how to setup the partitioning. We want to route the same messages belonging to the same id to the same queue, so its consumer will able to consume all the messages of that id. My questions: - From my understanding, in Kafka we would need to have a custom partitioner that routes the same messages to the same partition right? I'm trying to find examples of writing this partitioner logic, but I can't find any. Can
Re: Partitioning and scale
Hi Neha, Not sure if this sounds crazy, but if we'd like to have the events for the same session id go to the same partition one way could be that each session key creates its own topic with single partition, therefore there could be millions of topic with single partition. I wonder what would be the bottleneck of doing this? Thanks, Tim On Wed, May 22, 2013 at 4:32 PM, Neha Narkhede neha.narkh...@gmail.comwrote: Not automatically as of today. You have to run the reassign-partitions tool and explicitly move selected partitions to the new brokers. If you use this tool, you can move partitions to the new broker without any downtime. Thanks, Neha On Wed, May 22, 2013 at 2:20 PM, Timothy Chen tnac...@gmail.com wrote: Hi Neha/Chris, Thanks for the reply, so if I set a fixed number of partitions and just add brokers to the broker pool, does it rebalance the load to the new brokers (along with the data)? Tim On Wed, May 22, 2013 at 1:15 PM, Neha Narkhede neha.narkh...@gmail.com wrote: - I see that Kafka server.properties allows one to specify the number of partitions it supports. However, when we want to scale I wonder if we add # of partitions or # of brokers, will the same partitioner start distributing the messages to different partitions? And if it does, how can that same consumer continue to read off the messages of those ids if it was interrupted in the middle? The num.partitions config in server.properties is used only for topics that are auto created (controlled by auto.create.topics.enable). For topics that you create using the admin tool, you can specify the number of partitions that you want. After that, currently there is no way to change that. For that reason, it is a good idea to over partition your topic, which also helps load balance partitions onto the brokers. You are right that if you change the number of partitions later, then previously messages that stuck to a certain partition would now get routed to a different partition, which is undesirable for applications that want to use sticky partitioning. - I'd like to create a consumer per partition, and for each one to subscribe to the changes of that one. How can this be done in kafka? For your use case, it seems like SimpleConsumer might be a better fit. However, it will require you to write code to handle discovery of leader for the partition that your consumer is consuming. Chris has written up a great example that you can follow - https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+SimpleConsumer+Example Thanks, Neha On Wed, May 22, 2013 at 12:37 PM, Chris Curtin curtin.ch...@gmail.com wrote: Hi Tim, On Wed, May 22, 2013 at 3:25 PM, Timothy Chen tnac...@gmail.com wrote: Hi, I'm currently trying to understand how Kafka (0.8) can scale with our usage pattern and how to setup the partitioning. We want to route the same messages belonging to the same id to the same queue, so its consumer will able to consume all the messages of that id. My questions: - From my understanding, in Kafka we would need to have a custom partitioner that routes the same messages to the same partition right? I'm trying to find examples of writing this partitioner logic, but I can't find any. Can someone point me to an example? https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+Producer+Example The partitioner here does a simple mod on the IP address and the # of partitions. You'd need to define your own logic, but this is a start. - I see that Kafka server.properties allows one to specify the number of partitions it supports. However, when we want to scale I wonder if we add # of partitions or # of brokers, will the same partitioner start distributing the messages to different partitions? And if it does, how can that same consumer continue to read off the messages of those ids if it was interrupted in the middle? I'll let someone else answer this. - I'd like to create a consumer per partition, and for each one to subscribe to the changes of that one. How can this be done in kafka? Two ways: Simple Consumer or Consumer Groups: Depends on the level of control you want on code processing a specific partition vs. getting one assigned to it (and level of control over offset management). https://cwiki.apache.org/confluence/display/KAFKA/Consumer+Group+Example https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+SimpleConsumer+Example https://cwiki.apache.org/confluence/display/KAFKA/Consumer+Group+Example Thanks, Tim
Re: Partitioning and scale
Number of files to manage by os, I suppose. Why wouldn't you use consistent hashing with deliberately engineered collisions to generate a limited number of topics / partitions and filter at the consumer level? Regards Milind On May 23, 2013 4:22 PM, Timothy Chen tnac...@gmail.com wrote: Hi Neha, Not sure if this sounds crazy, but if we'd like to have the events for the same session id go to the same partition one way could be that each session key creates its own topic with single partition, therefore there could be millions of topic with single partition. I wonder what would be the bottleneck of doing this? Thanks, Tim On Wed, May 22, 2013 at 4:32 PM, Neha Narkhede neha.narkh...@gmail.com wrote: Not automatically as of today. You have to run the reassign-partitions tool and explicitly move selected partitions to the new brokers. If you use this tool, you can move partitions to the new broker without any downtime. Thanks, Neha On Wed, May 22, 2013 at 2:20 PM, Timothy Chen tnac...@gmail.com wrote: Hi Neha/Chris, Thanks for the reply, so if I set a fixed number of partitions and just add brokers to the broker pool, does it rebalance the load to the new brokers (along with the data)? Tim On Wed, May 22, 2013 at 1:15 PM, Neha Narkhede neha.narkh...@gmail.com wrote: - I see that Kafka server.properties allows one to specify the number of partitions it supports. However, when we want to scale I wonder if we add # of partitions or # of brokers, will the same partitioner start distributing the messages to different partitions? And if it does, how can that same consumer continue to read off the messages of those ids if it was interrupted in the middle? The num.partitions config in server.properties is used only for topics that are auto created (controlled by auto.create.topics.enable). For topics that you create using the admin tool, you can specify the number of partitions that you want. After that, currently there is no way to change that. For that reason, it is a good idea to over partition your topic, which also helps load balance partitions onto the brokers. You are right that if you change the number of partitions later, then previously messages that stuck to a certain partition would now get routed to a different partition, which is undesirable for applications that want to use sticky partitioning. - I'd like to create a consumer per partition, and for each one to subscribe to the changes of that one. How can this be done in kafka? For your use case, it seems like SimpleConsumer might be a better fit. However, it will require you to write code to handle discovery of leader for the partition that your consumer is consuming. Chris has written up a great example that you can follow - https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+SimpleConsumer+Example Thanks, Neha On Wed, May 22, 2013 at 12:37 PM, Chris Curtin curtin.ch...@gmail.com wrote: Hi Tim, On Wed, May 22, 2013 at 3:25 PM, Timothy Chen tnac...@gmail.com wrote: Hi, I'm currently trying to understand how Kafka (0.8) can scale with our usage pattern and how to setup the partitioning. We want to route the same messages belonging to the same id to the same queue, so its consumer will able to consume all the messages of that id. My questions: - From my understanding, in Kafka we would need to have a custom partitioner that routes the same messages to the same partition right? I'm trying to find examples of writing this partitioner logic, but I can't find any. Can someone point me to an example? https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+Producer+Example The partitioner here does a simple mod on the IP address and the # of partitions. You'd need to define your own logic, but this is a start. - I see that Kafka server.properties allows one to specify the number of partitions it supports. However, when we want to scale I wonder if we add # of partitions or # of brokers, will the same partitioner start distributing the messages to different partitions? And if it does, how can that same consumer continue to read off the messages of those ids if it was interrupted in the middle? I'll let someone else answer this. - I'd like to create a consumer per partition, and for each one to subscribe to the changes of that one. How can this be done in kafka? Two ways: Simple Consumer or Consumer Groups: Depends on the level of control you want on code processing a specific
Partitioning and scale
Hi, I'm currently trying to understand how Kafka (0.8) can scale with our usage pattern and how to setup the partitioning. We want to route the same messages belonging to the same id to the same queue, so its consumer will able to consume all the messages of that id. My questions: - From my understanding, in Kafka we would need to have a custom partitioner that routes the same messages to the same partition right? I'm trying to find examples of writing this partitioner logic, but I can't find any. Can someone point me to an example? - I see that Kafka server.properties allows one to specify the number of partitions it supports. However, when we want to scale I wonder if we add # of partitions or # of brokers, will the same partitioner start distributing the messages to different partitions? And if it does, how can that same consumer continue to read off the messages of those ids if it was interrupted in the middle? - I'd like to create a consumer per partition, and for each one to subscribe to the changes of that one. How can this be done in kafka? Thanks, Tim
Re: Partitioning and scale
Hi Tim, On Wed, May 22, 2013 at 3:25 PM, Timothy Chen tnac...@gmail.com wrote: Hi, I'm currently trying to understand how Kafka (0.8) can scale with our usage pattern and how to setup the partitioning. We want to route the same messages belonging to the same id to the same queue, so its consumer will able to consume all the messages of that id. My questions: - From my understanding, in Kafka we would need to have a custom partitioner that routes the same messages to the same partition right? I'm trying to find examples of writing this partitioner logic, but I can't find any. Can someone point me to an example? https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+Producer+Example The partitioner here does a simple mod on the IP address and the # of partitions. You'd need to define your own logic, but this is a start. - I see that Kafka server.properties allows one to specify the number of partitions it supports. However, when we want to scale I wonder if we add # of partitions or # of brokers, will the same partitioner start distributing the messages to different partitions? And if it does, how can that same consumer continue to read off the messages of those ids if it was interrupted in the middle? I'll let someone else answer this. - I'd like to create a consumer per partition, and for each one to subscribe to the changes of that one. How can this be done in kafka? Two ways: Simple Consumer or Consumer Groups: Depends on the level of control you want on code processing a specific partition vs. getting one assigned to it (and level of control over offset management). https://cwiki.apache.org/confluence/display/KAFKA/Consumer+Group+Example https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+SimpleConsumer+Examplehttps://cwiki.apache.org/confluence/display/KAFKA/Consumer+Group+Example Thanks, Tim
Re: Partitioning and scale
- I see that Kafka server.properties allows one to specify the number of partitions it supports. However, when we want to scale I wonder if we add # of partitions or # of brokers, will the same partitioner start distributing the messages to different partitions? And if it does, how can that same consumer continue to read off the messages of those ids if it was interrupted in the middle? The num.partitions config in server.properties is used only for topics that are auto created (controlled by auto.create.topics.enable). For topics that you create using the admin tool, you can specify the number of partitions that you want. After that, currently there is no way to change that. For that reason, it is a good idea to over partition your topic, which also helps load balance partitions onto the brokers. You are right that if you change the number of partitions later, then previously messages that stuck to a certain partition would now get routed to a different partition, which is undesirable for applications that want to use sticky partitioning. - I'd like to create a consumer per partition, and for each one to subscribe to the changes of that one. How can this be done in kafka? For your use case, it seems like SimpleConsumer might be a better fit. However, it will require you to write code to handle discovery of leader for the partition that your consumer is consuming. Chris has written up a great example that you can follow - https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+SimpleConsumer+Example Thanks, Neha On Wed, May 22, 2013 at 12:37 PM, Chris Curtin curtin.ch...@gmail.comwrote: Hi Tim, On Wed, May 22, 2013 at 3:25 PM, Timothy Chen tnac...@gmail.com wrote: Hi, I'm currently trying to understand how Kafka (0.8) can scale with our usage pattern and how to setup the partitioning. We want to route the same messages belonging to the same id to the same queue, so its consumer will able to consume all the messages of that id. My questions: - From my understanding, in Kafka we would need to have a custom partitioner that routes the same messages to the same partition right? I'm trying to find examples of writing this partitioner logic, but I can't find any. Can someone point me to an example? https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+Producer+Example The partitioner here does a simple mod on the IP address and the # of partitions. You'd need to define your own logic, but this is a start. - I see that Kafka server.properties allows one to specify the number of partitions it supports. However, when we want to scale I wonder if we add # of partitions or # of brokers, will the same partitioner start distributing the messages to different partitions? And if it does, how can that same consumer continue to read off the messages of those ids if it was interrupted in the middle? I'll let someone else answer this. - I'd like to create a consumer per partition, and for each one to subscribe to the changes of that one. How can this be done in kafka? Two ways: Simple Consumer or Consumer Groups: Depends on the level of control you want on code processing a specific partition vs. getting one assigned to it (and level of control over offset management). https://cwiki.apache.org/confluence/display/KAFKA/Consumer+Group+Example https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+SimpleConsumer+Example https://cwiki.apache.org/confluence/display/KAFKA/Consumer+Group+Example Thanks, Tim
Re: Partitioning and scale
Hi Neha/Chris, Thanks for the reply, so if I set a fixed number of partitions and just add brokers to the broker pool, does it rebalance the load to the new brokers (along with the data)? Tim On Wed, May 22, 2013 at 1:15 PM, Neha Narkhede neha.narkh...@gmail.comwrote: - I see that Kafka server.properties allows one to specify the number of partitions it supports. However, when we want to scale I wonder if we add # of partitions or # of brokers, will the same partitioner start distributing the messages to different partitions? And if it does, how can that same consumer continue to read off the messages of those ids if it was interrupted in the middle? The num.partitions config in server.properties is used only for topics that are auto created (controlled by auto.create.topics.enable). For topics that you create using the admin tool, you can specify the number of partitions that you want. After that, currently there is no way to change that. For that reason, it is a good idea to over partition your topic, which also helps load balance partitions onto the brokers. You are right that if you change the number of partitions later, then previously messages that stuck to a certain partition would now get routed to a different partition, which is undesirable for applications that want to use sticky partitioning. - I'd like to create a consumer per partition, and for each one to subscribe to the changes of that one. How can this be done in kafka? For your use case, it seems like SimpleConsumer might be a better fit. However, it will require you to write code to handle discovery of leader for the partition that your consumer is consuming. Chris has written up a great example that you can follow - https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+SimpleConsumer+Example Thanks, Neha On Wed, May 22, 2013 at 12:37 PM, Chris Curtin curtin.ch...@gmail.com wrote: Hi Tim, On Wed, May 22, 2013 at 3:25 PM, Timothy Chen tnac...@gmail.com wrote: Hi, I'm currently trying to understand how Kafka (0.8) can scale with our usage pattern and how to setup the partitioning. We want to route the same messages belonging to the same id to the same queue, so its consumer will able to consume all the messages of that id. My questions: - From my understanding, in Kafka we would need to have a custom partitioner that routes the same messages to the same partition right? I'm trying to find examples of writing this partitioner logic, but I can't find any. Can someone point me to an example? https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+Producer+Example The partitioner here does a simple mod on the IP address and the # of partitions. You'd need to define your own logic, but this is a start. - I see that Kafka server.properties allows one to specify the number of partitions it supports. However, when we want to scale I wonder if we add # of partitions or # of brokers, will the same partitioner start distributing the messages to different partitions? And if it does, how can that same consumer continue to read off the messages of those ids if it was interrupted in the middle? I'll let someone else answer this. - I'd like to create a consumer per partition, and for each one to subscribe to the changes of that one. How can this be done in kafka? Two ways: Simple Consumer or Consumer Groups: Depends on the level of control you want on code processing a specific partition vs. getting one assigned to it (and level of control over offset management). https://cwiki.apache.org/confluence/display/KAFKA/Consumer+Group+Example https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+SimpleConsumer+Example https://cwiki.apache.org/confluence/display/KAFKA/Consumer+Group+Example Thanks, Tim
Re: Partitioning and scale
Not automatically as of today. You have to run the reassign-partitions tool and explicitly move selected partitions to the new brokers. If you use this tool, you can move partitions to the new broker without any downtime. Thanks, Neha On Wed, May 22, 2013 at 2:20 PM, Timothy Chen tnac...@gmail.com wrote: Hi Neha/Chris, Thanks for the reply, so if I set a fixed number of partitions and just add brokers to the broker pool, does it rebalance the load to the new brokers (along with the data)? Tim On Wed, May 22, 2013 at 1:15 PM, Neha Narkhede neha.narkh...@gmail.com wrote: - I see that Kafka server.properties allows one to specify the number of partitions it supports. However, when we want to scale I wonder if we add # of partitions or # of brokers, will the same partitioner start distributing the messages to different partitions? And if it does, how can that same consumer continue to read off the messages of those ids if it was interrupted in the middle? The num.partitions config in server.properties is used only for topics that are auto created (controlled by auto.create.topics.enable). For topics that you create using the admin tool, you can specify the number of partitions that you want. After that, currently there is no way to change that. For that reason, it is a good idea to over partition your topic, which also helps load balance partitions onto the brokers. You are right that if you change the number of partitions later, then previously messages that stuck to a certain partition would now get routed to a different partition, which is undesirable for applications that want to use sticky partitioning. - I'd like to create a consumer per partition, and for each one to subscribe to the changes of that one. How can this be done in kafka? For your use case, it seems like SimpleConsumer might be a better fit. However, it will require you to write code to handle discovery of leader for the partition that your consumer is consuming. Chris has written up a great example that you can follow - https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+SimpleConsumer+Example Thanks, Neha On Wed, May 22, 2013 at 12:37 PM, Chris Curtin curtin.ch...@gmail.com wrote: Hi Tim, On Wed, May 22, 2013 at 3:25 PM, Timothy Chen tnac...@gmail.com wrote: Hi, I'm currently trying to understand how Kafka (0.8) can scale with our usage pattern and how to setup the partitioning. We want to route the same messages belonging to the same id to the same queue, so its consumer will able to consume all the messages of that id. My questions: - From my understanding, in Kafka we would need to have a custom partitioner that routes the same messages to the same partition right? I'm trying to find examples of writing this partitioner logic, but I can't find any. Can someone point me to an example? https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+Producer+Example The partitioner here does a simple mod on the IP address and the # of partitions. You'd need to define your own logic, but this is a start. - I see that Kafka server.properties allows one to specify the number of partitions it supports. However, when we want to scale I wonder if we add # of partitions or # of brokers, will the same partitioner start distributing the messages to different partitions? And if it does, how can that same consumer continue to read off the messages of those ids if it was interrupted in the middle? I'll let someone else answer this. - I'd like to create a consumer per partition, and for each one to subscribe to the changes of that one. How can this be done in kafka? Two ways: Simple Consumer or Consumer Groups: Depends on the level of control you want on code processing a specific partition vs. getting one assigned to it (and level of control over offset management). https://cwiki.apache.org/confluence/display/KAFKA/Consumer+Group+Example https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+SimpleConsumer+Example https://cwiki.apache.org/confluence/display/KAFKA/Consumer+Group+Example Thanks, Tim
