stanislavkozlovski

[2023-12-06 05:14:50,514] WARN maxCnxns is not configured, using default value 0. (org.apache.zookeeper.server.ServerCnxnFactory:309)
[2023-12-06 05:15:08,116] WARN [RequestSendThread controllerId=0] Controller 0's connection to broker localhost:45709 (id: 1 rack: null) was unsuccessful (kafka.controller.RequestSendThread:72)
java.net.SocketTimeoutException: Failed to connect within 1500 ms
	at kafka.controller.RequestSendThread.brokerReady(ControllerChannelManager.scala:299)
	at kafka.controller.RequestSendThread.doWork(ControllerChannelManager.scala:251)
	at org.apache.kafka.server.util.ShutdownableThread.run(ShutdownableThread.java:131)
[2023-12-06 05:15:10,365] WARN [RequestSendThread controllerId=0] Controller 0's connection to broker localhost:45709 (id: 1 rack: null) was unsuccessful (kafka.controller.RequestSendThread:72)
java.net.SocketTimeoutException: Failed to connect within 1500 ms
	at kafka.controller.RequestSendThread.brokerReady(ControllerChannelManager.scala:299)
	at kafka.controller.RequestS

stanislavkozlovski

[2023-12-06 10:16:32,684] WARN [RemoteLogManager=0 partition=R43Knpk9SrqUio5v0IZgyw:Follower-0] Current task for topic-partition R43Knpk9SrqUio5v0IZgyw:Follower-0 received error but it will be scheduled. Reason: Cannot invoke "scala.Option.isDefined()" because "leaderEpochCacheOpt" is null (kafka.log.remote.RemoteLogManager$RLMTask:818)
[2023-12-06 10:16:33,437] WARN [RemoteLogManager=0 partition=konHzmQ8Rk6B4NmkCs9H0A:Follower-0] Current task for topic-partition konHzmQ8Rk6B4NmkCs9H0A:Follower-0 received error but it will be scheduled. Reason: Cannot invoke "scala.Option.isDefined()" because "leaderEpochCacheOpt" is null (kafka.log.remote.RemoteLogManager$RLMTask:818)
[2023-12-06 10:16:33,934] WARN [RemoteLogManager=0 partition=i5cfg4VARQC17cJMCbjEzw:Leader-0] Current task for topic-partition i5cfg4VARQC17cJMCbjEzw:Leader-0 received error but it will be scheduled. Reason: Cannot invoke "org.apache.kafka.common.TopicPartition.topic()" because the return value of "kafka.log.UnifiedLog.topicPartition()" is null

stanislavkozlovski

[2023-12-06 07:29:20,263] WARN [QuorumController id=1000] Performing controller activation. Loaded ZK migration state of NONE. (org.apache.kafka.controller.QuorumController:204)
[2023-12-06 07:29:21,510] WARN [QuorumController id=1000] Performing controller activation. Loaded ZK migration state of NONE. (org.apache.kafka.controller.QuorumController:204)
[2023-12-06 07:29:23,153] WARN [QuorumController id=1000] Performing controller activation. Loaded ZK migration state of NONE. (org.apache.kafka.controller.QuorumController:204)
metaPropertiesEnsemble=MetaPropertiesEnsemble(metadataLogDir=Optional.empty, dirs={/tmp/kafka-11614840232121459491: EMPTY})
[2023-12-06 07:29:28,506] WARN [QuorumController id=1000] Performing controller activation. Loaded ZK migration state of NONE. (org.apache.kafka.controller.QuorumController:204)
[2023-12-06 07:29:29,354] WARN [QuorumController id=1000] Performing controller activation. Loaded ZK migration state of NONE. (org.apache.kafka.controller.QuorumController:204)
[2023-12-0

stanislavkozlovski

[2023-12-06 07:27:29,958] WARN maxCnxns is not configured, using default value 0. (org.apache.zookeeper.server.ServerCnxnFactory:309)
[2023-12-06 07:30:28,911] WARN [RequestSendThread controllerId=0] Controller 0's connection to broker localhost:37809 (id: 1 rack: null) was unsuccessful (kafka.controller.RequestSendThread:72)
java.net.SocketTimeoutException: Failed to connect within 1500 ms
	at kafka.controller.RequestSendThread.brokerReady(ControllerChannelManager.scala:299)
	at kafka.controller.RequestSendThread.doWork(ControllerChannelManager.scala:251)
	at org.apache.kafka.server.util.ShutdownableThread.run(ShutdownableThread.java:131)
[2023-12-06 07:31:01,656] WARN [RequestSendThread controllerId=0] Controller 0 epoch 1 fails to send request (type: UpdateMetadataRequest=, controllerId=0, controllerEpoch=1, kraftController=false, type=UNKNOWN, brokerEpoch=46, partitionStates=[], liveBrokers=UpdateMetadataBroker(id=1, v0Host='', v0Port=0, endpoints=[UpdateMetadataEndpoint(port=37809, host='localhost', list

stanislavkozlovski

A channel is simply a way a user discovers the product. An eternal law of the universe - every user discovers any product through some channel (even a grocery shop).

1. All users come from channels.
2. There are a fixed number of channels that exist in the world.
3. Channels are rigid. You must build your product to fit your channels.
4. Channels almost always have a power law of distribution.
5. Channels change over time, new channels give rise to new products.

Growth = product + channels

stanislavkozlovski

Looking at the Bitcoin Cash transctions for 18th Nov 2022 - blockchair_bitcoin-cash_transactions_20221118:

• https://gz.blockchair.com/bitcoin-cash/transactions/

import csv

size_sum = 0
num_tx = 0
with open('/Users/stanislavkozlovski/Downloads/blockchair_bitcoin-cash_transactions_20221118.tsv', newline='') as tsvfile:
 trash_reader = csv.reader(tsvfile, delimiter='\t', quotechar='|')

stanislavkozlovski

Titles

• Writer at 2 Minute Streaming and my socials (X, LinkedIn)
• Apache Kafka Committer
• previously a Staff I Software Engineer at Confluent in the Kafka Serverless Team. Amazing place, lots of growth both personal and company. Left to pursue other things after 6 years.

Some Words

I work hard to make an impact on whatever I am engaged in.

stanislavkozlovski

### Keybase proof

I hereby claim:

  * I am stanislavkozlovski on github.
  * I am kozlovski (https://keybase.io/kozlovski) on keybase.
  * I have a public key ASDpxv8GK3-OVSgHVZzJmJvxmc_8Ey_7QCR8IY_fq6p30go

To claim this, I am signing this object:

stanislavkozlovski

KafkaService-0-140353367942288
├── worker7
│   ├── kafka-data-logs-1
│   │   ├── __consumer_offsets-1
│   │   ├── __consumer_offsets-2
│   │   └── test_topic_1-0
│   └── kafka-data-logs-2
│       ├── __consumer_offsets-0
│       └── test_topic_2-0
├── worker8

stanislavkozlovski

gist -P -p -s