Gbase 8A common parallelism parameter adjustment to improve performance

explain

The thread pool parallelism parameter is set to the default value , The thread pool of the service may be small, resulting in a single error SQL The parallelism of tasks is too high , As a result, the post initiated tasks in the concurrent scenario cannot obtain sufficient thread pool and are executed by a single thread . In serious cases , Will cause more sys cpu Occupy . It can be adjusted according to the actual situation .

gcluser_max_thread_in_pool

The parameter means that the cluster layer connects all nodes in the cluster gnode The number of connection threads in the connection pool , That is, the size of the global connection thread pool , The default setting is 600.

The global thread pool is less used , The main logic is asynchronous API, Usually, just keep the default value .

When the cluster is large 、SQL When there are many concurrent tasks , If it is found that the higher the number of threads consumed in the connection pool , It's time to adjust gcluser_max_thread_in_pool Parameters , It is generally recommended not to exceed 2000. Too large a value can also cause performance problems .

gbase_parallel_degree

Used to configure a single SQL The degree of parallelism during execution , The default value is 0, Recommended configuration is 4~8. The value is 0 when , single sql The parallelism of tasks uses CPU Half the number of kernels . When the value is greater than the number of thread pools , Then the number of thread pools .

Such as ：gbase_parallel_degree=0,CPU Auditing for 32, So single sql The parallelism of is 16.

gbase_loader_parallel_degree

How many tasks each thread needs to load ,gbase_loader_parallel_degree Parameter is used to configure a single load task in gnode The degree of parallelism on , The default value is 0, That is to use CPU Half the number of kernels . Recommended configuration is 4~8.

The value is 0, Then use CPU Half the number of cores , When the value is greater than the number of thread pools , Then the number of thread pools .

gbase_parallel_max_thread_in_pool

Refers to the total number of threads in the thread pool , Used to configure the thread pool size , The default is CPU Nuclear 2 times , Deploy on each server 1 individual gnode This configuration is recommended for nodes CPU Nuclear 4~8 times .

Each task obtains threads from the thread pool and executes , When there are not enough free threads in the thread pool , Will be newly created 1 Threads for execution ( Internal serial ) Serial execution .

thread_pool_size

Indicates the number of thread pools used to receive client connections , Impact throughput .