* Do you want to know if your ZEO client cache is configured properly? * Are you using ZEO but you didn't know it had a client cache? * Do you want to contribute towards a better ZEO client cache design? If you answered yes at least once, read on! Jeremy is working on a new ZEO 2 release; the first beta was released two weeks ago. For that release I have written cache instrumentation code that lets you review the effectiveness of the ZEO client cache. There's also a version of the instrumented cache for ZEO 1. I don't plan to work on it more before the ZEO 2 release (unless I receive bug reports). All code is available *now* from the ZODB3 CVS tree: http://cvs.zope.org/ZODB3/. In addition to adding instrumentation, some bugs affecting performance but not correctness of the cache have been fixed in the instrumented cache code. The instrumentation is controlled by an environment variable so you can leave the new cache code in place after turning off the instrumentation. I'm inviting everyone who is running ZEO seriously to install the cache instrumentation code, run it for a while, and send me the resulting trace file. (The trace files contain no privacy-sensitive data, so you don't have to worry about revealing anything about your site.) The trace files will be used as input to a simulation of a new cache design. The only way to validate a cache design is to run experiments, and trace files are the most reliable way to run such experiments. The more trace files I receive the better. The larger they are the better (traces of several days of uninterrupted service are ideal). I've got the disk space to burn. I should mention that I'm confident that the instrumentated cache works correctly: we've been collecting traces without problems at a Zope Corp customer site since last Wednesday. To enable the cache instrumentation, you need to replace a single file in the ZEO package used by the Zope application, set an environment variable, and restart the Zope application. The file you need to replace is named ClientCache.py. Here are the URLs: For ZEO 1: http://cvs.zope.org/ZODB3/ZEO1/ClientCache.py?rev=HEAD For ZEO 2: http://cvs.zope.org/ZODB3/ZEO/ClientCache.py?rev=HEAD Make sure to get the file for the ZEO version you are using! Details about enabling the tracing can be found here: http://cvs.zope.org/ZODB3/ZEO/README.txt?rev=HEAD If you want to play with the statistics or simulation programs yourself, get stats.py and simul.py from the ZEO directory: http://cvs.zope.org/ZODB3/ZEO/ These work with trace files produced by either version of the instrumented cache code. Once you have one or more trace files for me, the best way to get it to me is probably to place a gzipped copy on an FTP or HTTP server from which I can download it and mail me the URL. As I said, these trace files contain no sensitive data. If you still prefer a different approach, email me and we'll figure something out. --Guido van Rossum (home page: http://www.python.org/~guido/)