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17:50:21.932509 IP myhost.39194 > host.31000: UDP, length 5 |
jstack tool
This is Java utility that provides important information about a Java process and execution threads.
When you run jstack from the console, a brief information about jstack is shown:
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If the information is not shown or the jstack utility is not found, use the installation instruction to latest version of JDK. After installing jdk you should create a symbolical link to jstack to quickly run it:
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Here, 8888 is the ID of the Java process.
Since build 5.2.801, WCS is running from 'flashphoner' user for security reasons. Therefore, jstack should be launched from the same user if using JDK 8:
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sudo -u `ps -o uname= -p $(pgrep java)` `which jstack` `pgrep java` |
Testing channel bandwidth using iperf
A stream published picture quality depends on channel bandwidth between publisher and server, the same for subscriber. Channel bandwidth can be checked using iperf utility. This program is implemented for all major OS: Windows, MacOS, Ubuntu/Debian, CentOS. iperf in server mode can be installed and running with WCS, that allows to check whole channel bandwith from publisher to viewer.
iperf can be installed on CentOS 7 as follows:
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yum install iperf3 |
Run iperf in server mode
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iperf3 -s -p 5201 |
where 5201 is iperf port for testing client connections
On client side iperf can be launched as follows:
1. To test upload channel bandwith via UDP (Windows example)
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iperf3.exe -c test2.flashphoner.com -p 5201 -u |
Where
- test2.flashphoner.com - WCS server
- 5201 - iperf port to connect
The result of the command above should look like this:
2. To test download channel bandwidth via UDP
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iperf3.exe -c test2.flashphoner.com -p 5201 -u -R |
Where
- test2.flashphoner.com - WCS server
- 5201 - iperf port to connect
The result of the command above should look like this:
By default, iperf tests the channel for 10 seconds. This interval should be increased, for example, to 120 second
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iperf3.exe -c test2.flashphoner.com -p 5201 -u -t 120 |
The upload channel bandwidth test via UDP result shows the maximum video publishing bitrate without packet losses. In the sample above bitrate should be limited with 1000 kbps, on server side for example
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webrtc_cc_max_bitrate=1000000 |
Note that iperf major versions on server and on testing client should be the same. Today version 3 is actual, but ther is also version 2 in repositories.