对std :: cout对程序性能的影响

Question

I have written a program which would fetch file details and place them in the SQLite database. In this process i have observed two scenarios:

Scenario 1:

1. Loop through each and every file and fill the file details(path) in to the database(sqlite3).
2. While for each file encountered,keep a counter and print the same via std::cout. Time taken to execute this program:30mins

Scenario 2:

1. Loop through each and every file and fill the file details(path) in to the database(sqlite3).

Time taken to execute this program:7mins

I am very unclear as of why just because of std::cout ,the time taken is 5 times more than that of not printing it?

Any pointers on this scenario is highly appreciated.Thanks a lot.

Regards, Ravi

Answer 1

尝试使用std::ios_base::sync_with_stdio(false) ，默认情况下std :: cout与stdio同步

Answer 2

Printing to console is costly. Usually more time-consuming than writing to a file.

I bet your code could run in less than a minute. Make sure you surround some inserts in a transaction . You can also use multiple inserts in one statement, like explained in answers to this question .