Are mature Java projects concurrent?

[fernandocastor]

This is the first issue specifically related to source code that must account for the actual language in which the project is implemented. To determine whether mature Java projects are concurrent, first we must define what is means to be concurrent and then we have to define what is a mature project. The first issue is easy: any project that employs at least one construct, either from the language or from a library (e.g., one synchronized block, one AtomicInteger, etc.) is considered to be concurrent.

As for maturity. we have to establish a proxy or a group of proxies for project maturity. Followers? # of commits? # of commits/day? # of forks? # of watchers? Activity of the contributors? Frequency of pull requests? # of lines of code?Age? Minimum thresholds for a number of criteria?

A related question that we must answer is what concurrent programming constructs do these projects use? How intensively?