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138 lines
4.9 KiB
Markdown
138 lines
4.9 KiB
Markdown
## NATS TOP Tutorial
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You can use [nats-top](natstop.md) to monitor in realtime NATS server connections and message statistics.
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#### Prerequisites
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- [Set up your Go environment](/documentation/additional_documentation/go-install/)
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- [Installed the NATS server](/documentation/managing_the_server/installing/)
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#### 1. Install nats-top
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```sh
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% go get github.com/nats-io/nats-top
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```
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You may need to run the following instead:
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```sh
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% sudo -E go get github.com/nats-io/nats-top
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```
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#### 2. Start the NATS server with monitoring enabled
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```sh
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% nats-server -m 8222
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```
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#### 3. Start nats-top
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```sh
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% nats-top
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```
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Result:
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```sh
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nats-server version 0.6.6 (uptime: 2m2s)
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Server:
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Load: CPU: 0.0% Memory: 6.3M Slow Consumers: 0
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In: Msgs: 0 Bytes: 0 Msgs/Sec: 0.0 Bytes/Sec: 0
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Out: Msgs: 0 Bytes: 0 Msgs/Sec: 0.0 Bytes/Sec: 0
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Connections: 0
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HOST CID SUBS PENDING MSGS_TO MSGS_FROM BYTES_TO BYTES_FROM LANG VERSION
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```
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#### 4. Run NATS client programs
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Run some NATS client programs and exchange messages.
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For the best experience, you will want to run multiple subscribers, at least 2 or 3. Refer to the [example pub-sub clients](/documentation/additional_documentation/nats-pub-sub).
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#### 5. Check nats-top for statistics
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```sh
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nats-server version 0.6.6 (uptime: 30m51s)
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Server:
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Load: CPU: 0.0% Memory: 10.3M Slow Consumers: 0
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In: Msgs: 56 Bytes: 302 Msgs/Sec: 0.0 Bytes/Sec: 0
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Out: Msgs: 98 Bytes: 512 Msgs/Sec: 0.0 Bytes/Sec: 0
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Connections: 3
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HOST CID SUBS PENDING MSGS_TO MSGS_FROM BYTES_TO BYTES_FROM LANG VERSION
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::1:58651 6 1 0 52 0 260 0 go 1.1.0
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::1:58922 38 1 0 21 0 105 0 go 1.1.0
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::1:58953 39 1 0 21 0 105 0 go 1.1.0
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```
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#### 6. Sort nats-top statistics
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In nats-top, enter the command `o` followed by the option, such as `bytes_to`. You see that nats-top sorts the BYTES_TO column in ascending order.
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```sh
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nats-server version 0.6.6 (uptime: 45m40s)
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Server:
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Load: CPU: 0.0% Memory: 10.4M Slow Consumers: 0
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In: Msgs: 81 Bytes: 427 Msgs/Sec: 0.0 Bytes/Sec: 0
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Out: Msgs: 154 Bytes: 792 Msgs/Sec: 0.0 Bytes/Sec: 0
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sort by [bytes_to]:
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Connections: 3
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HOST CID SUBS PENDING MSGS_TO MSGS_FROM BYTES_TO BYTES_FROM LANG VERSION
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::1:59259 83 1 0 4 0 20 0 go 1.1.0
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::1:59349 91 1 0 2 0 10 0 go 1.1.0
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::1:59342 90 1 0 0 0 0 0 go 1.1.0
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```
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#### 7. Use different sort options
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Use some different sort options to explore nats-top, such as:
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`cid`, `subs`, `pending`, `msgs_to`, `msgs_from`, `bytes_to`, `bytes_from`, `lang`, `version`
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You can also set the sort option on the command line using the `-sort` flag. For example: `nats-top -sort bytes_to`.
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#### 8. Display the registered subscriptions.
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In nats-top, enter the command `s` to toggle displaying connection subscriptions. When enabled, you see the subscription subject in nats-top table:
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```sh
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nats-server version 0.6.6 (uptime: 1h2m23s)
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Server:
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Load: CPU: 0.0% Memory: 10.4M Slow Consumers: 0
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In: Msgs: 108 Bytes: 643 Msgs/Sec: 0.0 Bytes/Sec: 0
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Out: Msgs: 185 Bytes: 1.0K Msgs/Sec: 0.0 Bytes/Sec: 0
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Connections: 3
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HOST CID SUBS PENDING MSGS_TO MSGS_FROM BYTES_TO BYTES_FROM LANG VERSION SUBSCRIPTIONS
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::1:59708 115 1 0 6 0 48 0 go 1.1.0 foo.bar
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::1:59758 122 1 0 1 0 8 0 go 1.1.0 foo
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::1:59817 124 1 0 0 0 0 0 go 1.1.0 foo
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```
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#### 9. Quit nats-top
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Use the `q` command to quit nats-top.
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#### 10. Restart nats-top with a specified query
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For example, to query for the connection with largest number of subscriptions:
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```sh
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% nats-top -n 1 -sort subs
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```
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Result: nats-top displays only the client connection with the largest number of subscriptions:
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```sh
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nats-server version 0.6.6 (uptime: 1h7m0s)
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Server:
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Load: CPU: 0.0% Memory: 10.4M Slow Consumers: 0
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In: Msgs: 109 Bytes: 651 Msgs/Sec: 0.0 Bytes/Sec: 0
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Out: Msgs: 187 Bytes: 1.0K Msgs/Sec: 0.0 Bytes/Sec: 0
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Connections: 3
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HOST CID SUBS PENDING MSGS_TO MSGS_FROM BYTES_TO BYTES_FROM LANG VERSION
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::1:59708 115 1 0 6 0 48 0 go 1.1.0
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```
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