Release Notes
NATS Concepts
Running a NATS service
Reference
Tutorial
Prerequisites
1. Install nats-top
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go install github.com/nats-io/nats-top
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You may need to run the following instead:
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sudo -E go install github.com/nats-io/nats-top
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2. Start the NATS server with monitoring enabled
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nats-server -m 8222
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3. Start nats-top
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nats-top
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Result:
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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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​
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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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4. Run NATS client programs
Run some NATS client programs and exchange messages.
For the best experience, you will want to run multiple subscribers, at least 2 or 3. Refer to the example pub-sub clients.
5. Check nats-top for statistics
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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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​
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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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6. Sort nats-top statistics
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.1
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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7. Use different sort options
Use some different sort options to explore nats-top, such as:
cid, subs, pending, msgs_to, msgs_from, bytes_to, bytes_from, lang, versionYou can also set the sort option on the command line using the
-sort flag. For example: nats-top -sort bytes_to.8. Display the registered subscriptions.
In nats-top, enter the command
s to toggle displaying connection subscriptions. When enabled, you see the subscription subject in nats-top table:1
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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​
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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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9. Quit nats-top
Use the
q command to quit nats-top.10. Restart nats-top with a specified query
For example, to query for the connection with largest number of subscriptions:
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nats-top -n 1 -sort subs
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Result: nats-top displays only the client connection with the largest number of subscriptions:
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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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​
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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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Contents
Prerequisites
1. Install nats-top
2. Start the NATS server with monitoring enabled
3. Start nats-top
4. Run NATS client programs
5. Check nats-top for statistics
6. Sort nats-top statistics
7. Use different sort options
8. Display the registered subscriptions.
9. Quit nats-top
10. Restart nats-top with a specified query