it does not seem to work on osx 10.10 using callbacks

[intersides]

If I place the example on a code using callbacks I get this result:

Writing to super large file
[112%] 879 bytes readWriting to super large file
[111%] 880 bytes readWriting to super large file
[110%] 881 bytes readWriting to super large file
[109%] 882 bytes readWriting to super large file
[108%] 883 bytes readWriting to super large file
... etc

Might this be an issue on MacOS only (10.10)

[freeall]

So it writes several lines and each of it goes over 100%?