>>Basic need for logging is the put the info into a file as fast as possible without any other intrusion.

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>I should be able to read and modify and delete log file while the process is running from Windows Explorer. With strtofile I can do that, with other suggested approaches I can not.
>
>I reverted to original code and only implemented write_log changes. So far so good although 1000 haven't finished yet and the log file is already 12 MB.

Thomas hit the nail on the head - you want a low-overhead logging process that writes a separate file to disk. The idea is to have a useful log file that survives even if your program crashes.

In the past I've had to fix schemes where log entries were written to a variable or property, the idea being to write it to disk at the end of processing. When the program errors or crashes, the variable/property is lost.

Although my log files rarely exceed a few Kbytes, I've had success using SET ALTERNATE TO filename ADDITIVE / SET ALTERNATE ON, then writing to the file with ?/??.