Track and manage process families
condor_procd -A address-file [options ]
condor_procd tracks and manages process families on behalf of the HTCondor daemons. It may track families of PIDs via relationships such as: direct parent/child, environment variables, UID, and supplementary group IDs. Management of the PID families include
registering new families or new members of existing families
getting usage information
signaling families for operations such as suspension, continuing, or killing the family
getting a snapshot of the tree of families
In a regular HTCondor installation, this program is not intended to be used or executed by any human.
The required argument, -A address-file, is the path and file name of the address file which is the named pipe that clients must use to speak with the condor_procd.
Print out usage information and exit.
Wait for the debugger. Initially sleep 30 seconds before beginning normal function.
- -C principal
The principal is the UID of the owner of the named pipe that clients must use to speak to the condor_procd.
- -L log-file
A file the condor_procd will use to write logging information.
When specified, another tool such as the procd_ctl tool must allocate the GID associated with a process. When this option is not specified, the condor_procd will allocate the GID itself.
- -P PID
If not specified, the condor_procd will use the condor_procd ‘s parent, which may not be PID 1 on Unix, as the parent of the condor_procd and the root of the tracking family. When not specified, if the condor_procd ‘s parent PID dies, the condor_procd exits. When specified, the condor_procd will track this PID family in question and not also exit if the PID exits.
- -S seconds
The maximum number of seconds the condor_procd will wait between taking snapshots of the tree of families. Different clients to the condor_procd can specify different snapshot times. The quickest snapshot time is the one performed by the condor_procd. When this option is not specified, a default value of 60 seconds is used.
- -G min-gid max-gid
If the -E option is not specified, then track process families using a self-allocated, free GID out of the inclusive range specified by min-gid and max-gid. This means that if a new process shows up using a previously known GID, the new process will automatically associate into the process family assigned that GID. If the -E option is specified, then instead of self-allocating the GID, the procd_ctl tool must be used to associate the GID with the PID root of the family. The associated GID must still be in the range specified. This is a Linux-only feature.
- -K windows-softkill-binary
This is the path and executable name of the condor_softkill.exe binary. It is used to send softkill signals to process families. This is a Windows-only feature.
Dealing with Short Reads¶
For unknown reasons, on Linux, attemps to read the list of PIDs from the /proc filesystem do not always return all of the PIDs on the system. The condor_procd attempts to detect when this occurs, using two methods.
If the list of PIDs does not include PID 1, the condor_procd’s own PID, or the PID of the condor_procd’s parent (which may be PID 1), then the list must be incomplete, and the condor_procd immediately retries the read.
Additionally, the condor_procd compares the number of PIDs it just read to the number of PIDs from the last time it (successfully) checked. If the number is too much smaller, it immediately retries. The default threshold is 0.90, meaning that if the current read has 90% or fewer of the last read’s PIDs, it’s considered invalid. In our testing, this threshold was met by roughly 1 in 4000 reads, but successfully detected all real short reads. If you need to adjust the threshold, you may do so by setting the environment variable _CONDOR_PROCAPI_RETRY_FRACTION. (In the normal case, simply have it in the environment when the condor_master starts up.)
If a retried read is incomplete (according to either method), the condor_procd returns the results of the previous read.
This program may be used in a stand alone mode, independent of HTCondor, to track process families. The programs procd_ctl and gidd_alloc are used with the condor_procd in stand alone mode to interact with the daemon and to inquire about certain state of running processes on the machine, respectively.
condor_procd will exit with a status value of 0 (zero) upon success, and it will exit with the value 1 (one) upon failure.