ApsaraDB for Redis:Test the synchronization latency between child instances in different regions

Overview

Global Distributed Cache for Redis is an active geo-redundancy database system that is developed based on ApsaraDB for Redis. Global Distributed Cache for Redis supports business scenarios in which multiple sites in different regions provide services at the same time. It helps enterprises replicate the active geo-redundancy architecture of Alibaba. For more information, see Overview.

Test environment

In this example, the distributed instance contains three child instances that reside in the China (Beijing), China (Shanghai), and China (Shenzhen) regions. Each child instance is deployed in a different region.

Test tool

The test tool is replicator-delay-test, which calculates the difference between the point in time when a key is read on the destination instance and the value of the key to obtain the latency.

Test method

In the following example, the latency is tested for data synchronization from the child instance in the China (Beijing) region to the child instance in the China (Shenzhen) region. The synchronization latency between child instances in other regions can be tested in the same way.

1. Log on to the ECS instance in the China (Shenzhen) region and run a command in the following format:

   java -jar replicator-delay-test.jar ${host} ${port} ${password} ${keynumber} get

   Note The test tool reads keys from the child instance in the China (Shenzhen) region. The keys were synchronized from the child instance in the China (Beijing) region. The test tool calculates the difference between the point in time when a key is read and the value of the key to obtain the latency.

   Parameter	Description
   {host}	The private endpoint of the child instance in the China (Shenzhen) region. For more information about how to obtain the private endpoint, see View endpoints.
   {port}	The port number that is used to connect to the child instance in the China (Shenzhen) region. Default value: 6379.
   {password}	The password that is used to connect to the child instance in the China (Shenzhen) region. Note If you use an account that is created on the child instance after the child instance is created, specify the password in the <user>:<password> format. For example, if the username of the account is admin and the password is Rp829dlwa, use admin:Rp829dlwa as the password to connect to the child instance.
   {keynumber}	The number of keys that you want to read.

2. Log on to the ECS instance in the China (Beijing) region and run a command in the following format:

   java -jar replicator-delay-test.jar ${host} ${port} ${password} ${keynumber} set

   Note The test tool continuously creates keys on the child instance in the China (Beijing) region. The test tool uses incremental integers as the names of the keys, and uses the timestamps when the keys are created as the values of the keys.

   Parameter	Description
   {host}	The private endpoint of the child instance in the China (Beijing) region. For more information about how to obtain the private endpoint, see View endpoints.
   {port}	The port number that is used to connect to the child instance in the China (Beijing) region. Default value: 6379.
   {password}	The password that is used to connect to the child instance in the China (Beijing) region. Note If you use an account that is created on the child instance after the child instance is created, specify the password in the <user>:<password> format. For example, if the username of the account is admin and the password is Rp829dlwa, use admin:Rp829dlwa as the password to connect to the child instance.
   {keynumber}	The number of keys that you want to write. It must be the same as the number of keys to read that you specify in Step 1.

3. Wait until the test tool on the ECS instance in the China (Shenzhen) region reads the specified number of keys. Then, the test tool displays the latency information about data synchronization from the child instance in the China (Beijing) region to the child instance in the China (Shenzhen) region.

Test result

The following metrics are provided in the Test result table:

Average latency

The average latency for synchronizing all keys in this test. Unit: milliseconds.

95th

The highest latency that is obtained when 95% of the keys are synchronized. Unit: milliseconds. For example, if the value of this metric is 20 milliseconds, 95% of the keys are synchronized within 20 milliseconds.

99th

The highest latency that is obtained when 99% of the keys are synchronized. Unit: milliseconds. For example, if the value of this metric is 50 milliseconds, 99% of the keys are synchronized within 50 milliseconds.