Fix http 503 Service Unavailable Example

http 503 Error: Your web server is currently unable to process HTTP requests due to temporary overload or temporary maintenance.

First of all, to find the root cause of the 503 bottleneck, it may be in the database, there may be disk IO, there may be more than the number of network connections.

In Performance Monitor, the web service > Current Connections connection is at 20000+, and the database connection and disk IO are within reasonable limits, so basically the number of connections is too large. PS: Generally, you have a certain understanding of the traffic volume of your website. The poor server can't stand more than 40,000 IP.

The number of connections for 2w+ is not large, but why it causes a 503 error, and the execution time of a single request from the performance monitor is also very short, which indicates that the processing capacity of the IIS application pool is Not on.

After adjusting the number of threads in the application pool, increasing from 1 to 4 (as shown below), the queue length increased from 1000 to 6000, and then, through performance monitoring, it was found that Current Connections fell below 1w, 503 error It disappeared.

PS: Currently a lot of tutorials on the web are saying is recommended to use the default WEB Park 1, it is really the process of pooling, however, shorten recovery time but it is very low, then the number of modified process will be a more The ideal solution.