How long does it usually take for a patch to be reviewed?

I submitted a patch to Phabricator and issued a review request 10 days ago but it hasn’t been reviewed until now.

Chuyang Chen
MSc Student
At Department of Computer Science and Technology, Nanjing University

You can “ping” the reviewers (by saying “ping” in comments) every now and then. You can’t expect an immediate reaction but pinging every 1-2 weeks is considered to be polite. Consider bringing in more reviewers. Sometimes you may also make reviewing your patch easier by providing a better summary, adding comments to the code, or generally explaining why do you believe that your patch is the right solution to the problem it’s trying to solve.

Hi Chuyang,

If your patch hasn't been reviewed for a long time, you can ping
reviewers on Phabricator.

Ping @reviewer1 @reviewer2 ...

FTR, the patch is titled:

 [clang] Change the multi-character character constants from extension to implementation-defined.

As Artem said the issue here is probably that a single reviewer is not enough and patches can slip through the cracks.
More reviewers, and pings (which generate emails on the appropriate list) can help. To find reviewers it's often good to
blame the lines you modified or lines around it. Unfortunately, the main changes in the lexer were last touched a decade
ago by Chris, unclear if that is of much help. Eli added the lines in p1.cpp also a decade ago, Jordan Rose the FixIt lines.