Frequently Asked Questions

Technical Issues

Missing standard library when compiling on macOS

If you get an error when running make develop (or python develop) that says fatal error: 'iostream' file not found, this is likely because latest versions of macOS put the standard C++ libraries inside a package, rather than in /usr/lib (where older versions of setuptools expect them to be apparently). If this error occurs, you can just run the following command to re-create the /usr/lib links:

sudo installer -pkg /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg -target /

Hard crash when loading a SimTelArray file?

Note: as of ctapipe 0.6.1, the new SimTelEventSource (based on pyeventio) is used by default instead of HESSIOEventSource (based on pyhessio/libhessio). This should prevent any crashes as it does not use the libhessio library. If you are still using an older version, or have explicitly enabled the HESSIOEventSource rather than the new SimTelEventSource, see the following:

Sometimes when reading a simtel file, the code crashes (not even an out-of-memory error is given). Loading a simtel file right now needs a lot of ram. However, a second issue with SimTelArray files is that we have compiled libhessio to allow very large arrays (>500 telescopes, with high-resolution cameras like the SCTCam), and this sometimes causes memory allocation to hit your OS’s stack limit. THis issue will go away when the final array layout is fixed (at which point we will no longer support reading older simtelarray files, however). In the mean time, you can increase your stack memory limit by using the commmand ulimit -s for a single terminal session. Increasing it above the default should help stop these random crashes.