How do I love Valgrind? Let me count the ways.

Valgrind is a neat little tool that replaced the memory handling routines of the operating system with specially instrumented ones that also keep track of everything you are doing with memory. Then, if you don't free it, Valgrind can tell you.

All of this will seem unspeakably primitive to our Java programming friends. Sorry to bring up such a barbaric topic as memory management.

Like any such tool, when Valgrind was first used on netCDF code it issued many warnings and error reports. Most were actually warnings and memory errors in the test programs themselves (which don't get the kind of attention that the library code does - who tests their tests?) But some of the Valgrind messages pointed to real memory bugs in either HDF5 or netCDF-4.

The HDF5 team has been very pro-active in hunting down all the memory problems this process has uncovered, and since 1.8.4 have been tightening up memory handling by HDF5. Meanwhile I have been doing the same for netCDF-4 code.

The result is that (in my branch of the repository - soon to be merged into the main branch) there are very few memory leaks of any kind, and almost all the libsrc4 test programs now pass Valgrind with no errors or warnings. These changes will be part of the performance and bugfix release 4.1.2.

I love Valgrind because all previous tools I've used for this have been rather clumsy. Valgrind is the easiest way to memory test a program!