Prerequisite
- Install Redis service (daemon) on your Moodle server (see https://docs.moodle.org/37/en/Redis_cache_store#Installing_Redis_server) if you do not already have it.
- Install the PHP extension Redis (see https://docs.moodle.org/37/en/Redis_cache_store#Installing_Redis_php_driver) if you do not already have it.
- Start the Redis daemon (eg. redis-server /usr/local/etc/redis.conf).
- Install the PHP extension zstd see https://github.com/kjdev/php-ext-zstd for information on ways to install this by reading the README.
- Create a couple test courses with activities. This will just be needed to navigate around and simulate a session. The Moodle tool for creating courses is useful to quickly make test courses (/admin/tool/generator/maketestcourse.php)
Configuration
Add the following to the config.php file
$CFG->session_handler_class = '\core\session\redis';
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$CFG->session_redis_host = '127.0.0.1';
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Test 1 (no compression)
- Clear the local Redis data
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127.0.0.1:6379> config resetstat
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- Login to Moodle
- Navigate around the test courses and some activities. (Note each course and activity visited, as it's important to visit the same courses for each compression type.)
- Check the session data in redis-cli tool
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- Use that key to view data
127.0.0.1:6379> get {keyfromlaststep}
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- Note the data is a string representation of an object with human readable keys (i.e. lastname, email)
- Get the performance stats from redis-cli:
127.0.0.1:6379> info stats
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- Take a note of the total_net_input_bytes value and total_net_output_bytes value
Test 2 (gzip compression)
Add this line to the config.php
$CFG->session_redis_compressor = 'gzip';
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Repeat test 1 making sure to visit the same courses and activities as before. On the last step note that the data is no longer human readable and compressed.
Verify the output from the redis-cli get command is no longer human readable.
Verify that the total_net_input_bytes and total_net_output_bytes values have decreased.
Test 3 (zstd compression)
Modify the $CFG->session_redis_compressor value set in config.php from 1 to 2
$CFG->session_redis_compressor = 'zstd';
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Repeat test 1 making sure to visit the same courses and activities as before.
Verify the output from the redis-cli get command is no longer human readable.
Verify that the total_net_input_bytes and total_net_output_bytes values have decreased.
Test 4 (unit tests)
Add the following to your config.php file
define('TEST_CACHESTORE_REDIS_TESTSERVERS', '127.0.0.1');
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Run the unit tests
vendor/bin/phpunit lib/tests/session_redis_test.php
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Improvement
Minor
