A respected technical journal in Germany, c't, said it has discovered a bug in Mac OS X server that potentially limits the effectiveness of the software for use in hosting Web sites.
The problem has been shown to occur under simulated situations when a relatively small number of users interact with a Web site through common gateway interface (CGI) scripts. The Apache Web server software that comes with Mac OS X Server will crash the system when 32 copies of a built-in benchmark program call CGI scripts simultaneously. This test represents how users numbering in the hundreds would stress a server; the server should only slow down when users numbering into the thousands are simultaneously accessing a site.
CGI scripts allow the Web server to automatically perform tasks such as retrieving information from a form on a Web page, or storing information in a database to present a custom page. These programs are a common element to many Web sites.
"The main problem is that every Mac OS X Server running in the Internet can be easily crashed by remote," said Stephan Ehrmann senior editor of c't, in an email to CNET News.com.
The problem described by c't can be curtailed, said one chief technology officer who wrote to CNET News.com, by disabling or removing the benchmark program from Apache. He said the problem does not occur with other CGI scripts "that we know of at this time."
The possibility remains that there could be other scripts that could be affected, however, based on users posting messages to Apple's technical support site.
C't hypothesized that the problem lies with Apple's implementation of Unix in the operating systems because the Apache software does not experience the same problems on other Unix or Windows NT servers.
"We're aware of the test, and we believe that this is only a problem that a benchmark could cause," said Russell Brady, a spokesperson for Apple. "It probably wouldn't be replicated in real life, but at the same time, we're looking to solve it."
Ehrman said that the problem occurs with a number of scripts other than their original test script, which was posted on their Web site.
User feedback initially seems to be divided on the issue. One user reported no problems when using CGI scripts on Apple's technical support site, while another reported that they experienced the problems noted by c't.
The problem doesn't likely affect many users--yet. Mac OS X Server is Apple's operating system software for back-end computing functions that started shipping in March. Mac OS X has a more limited audience than the version of the Mac OS used on regular desktop and notebook Macs.
However, the software marks a significant effort by Apple to provide reliable, high-performance software for server computers. It is a market where Apple has not had a significant presence compared to companies such as Microsoft and Sun Microsystems, among others that also offer server computer operating systems. Some potential corporate customers might shy away from using Apple's software if too many questions about the reliability of the software crops up, although this bug appears to be one of the first notable problems reported.
Apple plans on developing a software fix for the problem but doesn't have a timeframe for when the fix will be released yet.