Hi, I do producer(Kafka 0.8) throughput test many times. But the average value is 3MB/S. Below is my test environment: CPU core :16 Vendor_id £ºGenuineIntel Cpu family £º6 Cpu MHz :2899.999 Cache size :20480 KB Cpu level :13 MEM :16330832KB=15.57GB Disk : RAID5
I don¡¯t know the detail information about the disk, such as rotation. But I do some test about the I/O performance of the disk. The write rate is 500MB~600MB/S, the read rate is 180MB/S. The detail is as below. [cid:[EMAIL PROTECTED]6900]
And I adjust the broker configuration file as the official document says as below. And I adjust the JVM to 5120MB. I run producer performance test with the script kafka-producer-perf-test.sh, with the test command is bin/kafka-producer-perf-test.sh --broker-list 10.75.167.46:49092 --topics topic_perf_46_1,topic_perf_46_2,topic_perf_46_3,topic_perf_46_4, topic_perf_46_5,topic_perf_46_6, topic_perf_46_7,topic_perf_46_8,topic_perf_46_9,topic_perf_46_10 --initial-message-id 0 --threads 200 --messages 1000000 --message-size 200 --compression-codec 1
But the test result is also not as good as the official document says(50MB/S, and that value in your paper is 100MB/S). The test result is as below: 2013-01-17 04:15:24:768, 2013-01-17 04:25:01:637, 0, 200, 200, 1907.35, 3.3064, 10000000, 17334.9582
On the other hand, I do consumer throughput test, the result is about 60MB/S while that value in official document is 100MB/S. I really don¡¯t know why? You know high throughput is one of the most important features of Kafka. So I am really concerned with it.
Thanks and best regards!
From: Jay Kreps [mailto:[EMAIL PROTECTED]] Sent: 2013Äê1ÔÂ16ÈÕ 2:22 To: Jun Guo -X (jungu - CIIC at Cisco) Subject: RE: About acknowledge from broker to producer in your paper.
Not sure which version you are using...
In 0.7 this would happen only if there was a socket level error (i.e. can't connect to the host). This covers a lot of cases since in the event of I/O errors (disk full, etc) we just have that node shut itself down to let others take over.
In 0.8 we send all errors back to the client.
So the difference is that, for example, in the event of a disk error, in 0.7 the client would send a message, the broker would get an error and shoot itself in the head and disconnect its clients, and the client would get the error the next time it tried to send a message. So in 0.7 the error might not get passed back to the client until the second message send. In 0.8 this would happen with the first send, which is an improvement.
-Jay ________________________________ From: Jun Guo -X (jungu - CIIC at Cisco) [[EMAIL PROTECTED]] Sent: Monday, January 14, 2013 9:45 PM To: Jay Kreps Subject: About acknowledge from broker to producer in your paper. Hi, I have read your paper Kafka: a Distributed Messaging System for Log Processing . In experimental results part. There are some words as below:
There are a few reasons why Kafka performed much better. First, the Kafka producer currently doesn¡¯t wait for acknowledgements from the broker and sends messages as faster as the broker can handle. This significantly increased the throughput of the publisher. With a batch size of 50, a single Kafka producer almost saturated the 1Gb link between the producer and the broker. This is a valid optimization for the log aggregation case, as data must be sent asynchronously to avoid introducing any latency into the live serving of traffic. We note that without acknowledging the producer, there is no guarantee that every published message is actually received by the broker. For many types of log data, it is desirable to trade durability for throughput, as long as the number of dropped messages is relatively small. However, we do plan to address the durability issue for more critical data in the future.
But I have done a series of test. I found that ,if I shut down all the brokers, when I send a message from producer to broker, the producer will report kafka.common.FailedToSendMessageException . It says, Failed to send messages after 3 tries. [cid:[EMAIL PROTECTED]ED00] If there is no acknowledge from broker, how the producer find the sending is failed? And how it try 3 times?
Maybe, the acknowledge in your paper refers to another thing, if so ,please tell what is the meaning of acknowledge?
We also did some perf test on 0.8 using the following command. All configs on the broker are the defaults. bin/kafka-run-class.sh kafka.perf.ProducerPerformance --broker-list localhost:9092 --initial-message-id 0 --messages 2000000 --topics topic_001
The following is our preliminary result. Could you try this on your environment? For replication factor larger than 1, we will try ack=1 and report the numbers later. It should provide better throughput. Thanks,
*No. of Brokers = 1 / Replication Factor = 1 (Partition = 1)**Producer threads**comp**msg size**Acks**batch**Thru Put (MB/s)*101024-115.49201024-11 9.38501024-1116.611001024-1119.54101024-15025.72201024-15039.25501024-150 54.171001024-15056.71101024-110027.97201024-110045.05501024-110058.011001024 -110059.82*No. of Brokers = 2 / Replication Factor = 2 (Partitions = 1)**Producer threads**comp**msg size**Acks**batch**Thru Put (MB/s)*101024-110.58201024-11 1.17501024-111.601001024-113.15101024-1507.48201024-15013.89501024-15018.11 1001024-15020.91101024-11008.72201024-110016.84501024-110020.661001024-1100 23.82*No. of Brokers = 3 / Replication Factor = 3 (Partitions = 1)**Producer threads**comp**msg size**Acks**batch**Thru Put (MB/s)*101024-110.53201024-11 0.94501024-111.721001024-112.78101024-1507.08201024-15013.40501024-15018.11 1001024-15021.01101024-11008.09201024-110014.88501024-110019.931001024-1100 23.22 Thanks,
On Wed, Jan 16, 2013 at 8:33 PM, Jun Guo -X (jungu - CIIC at Cisco) < [EMAIL PROTECTED]> wrote:
These tests measure producer throughput in the worst case scenario (producer.num.acks=-1) i.e. max durability setting. The baseline with 0.7 would be to compare producer throughput with num.acks=0. We are working on those tests now.
Thanks, Neha On Thu, Jan 17, 2013 at 8:43 AM, Jun Rao <[EMAIL PROTECTED]> wrote:
There is still a difference between the 0.7 and 0.8 Kafka behavior in the sense that in 0.7, the producer fired away requests at the broker without waiting for an ack. In 0.8, even with num.acks=0, the producer writes are going to be synchronous and it won't be able to send the next request until the ack for the previous one comes back.
Thanks, Neha On Fri, Jan 18, 2013 at 12:24 PM, S Ahmed <[EMAIL PROTECTED]> wrote:
I see, so that is a fairly substantial change, ofcourse it has its advantage of guaranteeing a higher degree of durability but as a significant cost (round trip that the consumer has to wait for). I know someone mentioned creating a asych. consumer with a future.
Do you have a 'gut' feeling performance will be the same as in .7 or x% slower? (or you have no idea as of yet as you guys are still going to work on perf) On Fri, Jan 18, 2013 at 8:42 PM, Neha Narkhede <[EMAIL PROTECTED]>wrote:
As mentioned we have some experience running this with no ack and there are a lot of downsides. We considered making the ack optional, but this would complicate the producer api since we could give back the offset only in the case where there is an ack.
Thinking about it more we realized there is no real performance hit, just latency, and you only pay for the latency if you want to wait for the response. This resulted in the current tentative plan which is to make all requests async, always return "future response" so you only block if you want to get the result. This is the best possible end-state since we can give the rich general api with the same performance as without the ack.
However this requires a fairly large change in the client which we haven't done yet.
So in 0.8 synchronous producer performance will decrease. Asynchronous production should probably not be too much worse because the async production and batching masks and amortizes the latency. It is too early to say how much worse it will be as there are still a few perf issues to resolve.
It would be reasonable if people were a little annoyed by this since we are effectively making the software worse on some dimensions before we make it better. Our reasoning was that batching up even more changes into a single release was just too dangerous. People who care about replication will (hopefully) care enough about this that taking a hit on sync producer performance will be okay, and people who don't care about replication can just skip a version since that is the major feature in 0.8.
-Jay On Tue, Jan 22, 2013 at 7:10 PM, S Ahmed <[EMAIL PROTECTED]> wrote:
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