RE: Consume more than produce
Hey I had an issue in the production two days ago, For some reason 2 brokers in my 5 brokers cluster were stuck, meaning their process was up, but they didn't answer to port 9092. The ZK saw them as live brokers. Producer couldn't produce events to them and consumer couldn't consume Solving the issue I restarted the brokers, and also I stopped all the consumers I had, and started them again. Before I try to understand what happened to the brokers, I want to show you what happened to the data in my system. [cid:image001.png@01CFB585.69F27950] The orange line is the number of events the consumer consumed The blue line is the number of events the producer produced. When there is the differences it's the time the brokers did their troubles. I guess the problem was the consumer didn't commit the msgs, or something like that, but if that is so, why did the consumer continued consuming, might that help me understand the problem I have in general that even when times are regular the consumer consumes more the producer? Thanks. -Original Message- From: Guy Doulberg [mailto:guy.doulb...@perion.com] Sent: Monday, August 04, 2014 2:12 PM To: users@kafka.apache.org Subject: RE: Consume more than produce Hi Daniel I count once when producing and count once when consuming, the timestamp is calculated once before producing, and it is being attached to the msg so the consumer will use the same TS to count Thanks -Original Message- From: Daniel Compton [mailto:d...@danielcompton.net] Sent: Monday, August 04, 2014 12:35 PM To: users@kafka.apache.orgmailto:users@kafka.apache.org Subject: Re: Consume more than produce Hi Guy In your reconciliation, where was the time stamp coming from? Is it possible that messages were delivered several times but your calculations only counted each unique event? Daniel. On 4/08/2014, at 5:35 pm, Guy Doulberg guy.doulb...@perion.commailto:guy.doulb...@perion.com wrote: Hi What do you mean producer ACK value? In my code I don't have a retry mechanism, the Kafka producer API has a retry mechanism? -Original Message- From: Guozhang Wang [mailto:wangg...@gmail.com] Sent: Friday, August 01, 2014 6:08 PM To: users@kafka.apache.orgmailto:users@kafka.apache.org Subject: Re: Consume more than produce What is the ack value used in the producer? On Fri, Aug 1, 2014 at 1:28 AM, Guy Doulberg guy.doulb...@perion.commailto:guy.doulb...@perion.com wrote: Hey, After a year or so I have Kafka as my streaming layer in my production, I decided it is time to audit, and to test how many events do I lose, if I lose events at all. I discovered something interesting which I can't explain. The producer produces less events that the consumer group consumes. It is not much more, it is about 0.1% more events I use the Consumer API (not the simple consumer API) I was thinking I might had rebalancing going on in my system, but it doesn't look like that. Did anyone see such a behaviour In order to audit, I calculated for each event the minute it arrived, and assigned this value to the event, I used statsd do to count all events from all my producer cluster, and all consumer group cluster. I must say that it is not a happening for every minute, Thanks, Guy -- -- Guozhang
RE: Consume more than produce
If you can't see the image, I uploaded it to dropbox https://www.dropbox.com/s/gckn4gt7gv26l9w/graph.png From: Guy Doulberg [mailto:guy.doulb...@perion.com] Sent: Monday, August 11, 2014 4:58 PM To: users@kafka.apache.org Subject: RE: Consume more than produce Hey I had an issue in the production two days ago, For some reason 2 brokers in my 5 brokers cluster were stuck, meaning their process was up, but they didn't answer to port 9092. The ZK saw them as live brokers. Producer couldn't produce events to them and consumer couldn't consume Solving the issue I restarted the brokers, and also I stopped all the consumers I had, and started them again. Before I try to understand what happened to the brokers, I want to show you what happened to the data in my system. [cid:image001.png@01CFB585.69F27950] The orange line is the number of events the consumer consumed The blue line is the number of events the producer produced. When there is the differences it's the time the brokers did their troubles. I guess the problem was the consumer didn't commit the msgs, or something like that, but if that is so, why did the consumer continued consuming, might that help me understand the problem I have in general that even when times are regular the consumer consumes more the producer? Thanks. -Original Message- From: Guy Doulberg [mailto:guy.doulb...@perion.com] Sent: Monday, August 04, 2014 2:12 PM To: users@kafka.apache.orgmailto:users@kafka.apache.org Subject: RE: Consume more than produce Hi Daniel I count once when producing and count once when consuming, the timestamp is calculated once before producing, and it is being attached to the msg so the consumer will use the same TS to count Thanks -Original Message- From: Daniel Compton [mailto:d...@danielcompton.net] Sent: Monday, August 04, 2014 12:35 PM To: users@kafka.apache.orgmailto:users@kafka.apache.org Subject: Re: Consume more than produce Hi Guy In your reconciliation, where was the time stamp coming from? Is it possible that messages were delivered several times but your calculations only counted each unique event? Daniel. On 4/08/2014, at 5:35 pm, Guy Doulberg guy.doulb...@perion.commailto:guy.doulb...@perion.com wrote: Hi What do you mean producer ACK value? In my code I don't have a retry mechanism, the Kafka producer API has a retry mechanism? -Original Message- From: Guozhang Wang [mailto:wangg...@gmail.com] Sent: Friday, August 01, 2014 6:08 PM To: users@kafka.apache.orgmailto:users@kafka.apache.org Subject: Re: Consume more than produce What is the ack value used in the producer? On Fri, Aug 1, 2014 at 1:28 AM, Guy Doulberg guy.doulb...@perion.commailto:guy.doulb...@perion.com wrote: Hey, After a year or so I have Kafka as my streaming layer in my production, I decided it is time to audit, and to test how many events do I lose, if I lose events at all. I discovered something interesting which I can't explain. The producer produces less events that the consumer group consumes. It is not much more, it is about 0.1% more events I use the Consumer API (not the simple consumer API) I was thinking I might had rebalancing going on in my system, but it doesn't look like that. Did anyone see such a behaviour In order to audit, I calculated for each event the minute it arrived, and assigned this value to the event, I used statsd do to count all events from all my producer cluster, and all consumer group cluster. I must say that it is not a happening for every minute, Thanks, Guy -- -- Guozhang
Re: Consume more than produce
You have to remember statsd uses udp and possibly lossy which might account for the errors. -Steve On Fri, Aug 1, 2014 at 1:28 AM, Guy Doulberg guy.doulb...@perion.com wrote: Hey, After a year or so I have Kafka as my streaming layer in my production, I decided it is time to audit, and to test how many events do I lose, if I lose events at all. I discovered something interesting which I can't explain. The producer produces less events that the consumer group consumes. It is not much more, it is about 0.1% more events I use the Consumer API (not the simple consumer API) I was thinking I might had rebalancing going on in my system, but it doesn't look like that. Did anyone see such a behaviour In order to audit, I calculated for each event the minute it arrived, and assigned this value to the event, I used statsd do to count all events from all my producer cluster, and all consumer group cluster. I must say that it is not a happening for every minute, Thanks, Guy
Re: Consume more than produce
Do you have producer retries (due to broker failure) in those minutes when you see a diff? Thanks, Jun On Fri, Aug 1, 2014 at 1:28 AM, Guy Doulberg guy.doulb...@perion.com wrote: Hey, After a year or so I have Kafka as my streaming layer in my production, I decided it is time to audit, and to test how many events do I lose, if I lose events at all. I discovered something interesting which I can't explain. The producer produces less events that the consumer group consumes. It is not much more, it is about 0.1% more events I use the Consumer API (not the simple consumer API) I was thinking I might had rebalancing going on in my system, but it doesn't look like that. Did anyone see such a behaviour In order to audit, I calculated for each event the minute it arrived, and assigned this value to the event, I used statsd do to count all events from all my producer cluster, and all consumer group cluster. I must say that it is not a happening for every minute, Thanks, Guy
