I've managed to crash Erlyweb/Yaws, but only under a colossal load and in a fairly unusual situation.
I was using Erlyweb to create traffic for a series of mainframe capacity tests. The broad approach was: - fill in details on an Erlyweb page of the mainframe transaction and the data for that transaction - Erlyweb then constucts an appropriate network packet and sends it to mainframe - Erlyweb waits for a response from the mainframe and compares the response with what Erlyweb has calculated it should be (plus a few small variations on that approach). The whole thing was driven by HP's LoadRunner tool, which was simulating several hundred users hitting the Erlyweb interface as fast as they could. As the workload increased, the responses from the mainframe started to slow down; eventually I forced the mainframe to timeout after 20 seconds, but that wasn't the case throughout all of the testing. Under some pretty extreme loads - around 20,000 open mainframe connections - I was blowing up Erlyweb/Yaws. As a sanity check, this was when Erlyweb/Yaws was consuming ~90% of all 4 CPUs on a dedicated newish Dell server running Ubuntu 7.10 server; there was probably smoke coming out of the box at the time ;-> On occasion, I was also blowing up CICS on the mainframe (a Z9 series, so pretty new gear) with workload supplied by this single Erlyweb box on occasion, so maybe we were getting into some weird sort of temporal, black-hole type situation where the universe was starting to fold in on itself ;-> There's nothing like applying extreme workloads to show up some really strange problems. Unfortunately, I didn't capture the error message; I was short of time, this was my first serious use of Erlyweb so I'm not 100% convinced it wasn't a problem of my own making, OTP was recovering things properly for me when it broke so I didn't really care that much, and the workload I was applying was far enough above what was required that it didn't matter for the purpose of the tests. For that particular application, we were running at a steady state of about 500,000 "pages served" from Erlyweb per hour, with peaks of up to about 2 million pages per hour, for durations of up to 6 hours at a time. To put it mildly, I was extremely impressed with the robustness of the architecture; there's no way that any comparable Apache/WebSphere or IIS/ASP.NET-based solution could have survived that workload. I'm now moving some of my older C and Java server code over to Erlang based on the results of this testing; not sure if I'll be using Erlyweb as part of this migration, but its scalability and reliability were definitely a big part of my decision to do so. Regards Dave Mitchell 2008/5/2 bill robertson <[EMAIL PROTECTED]>: > > If I can ask a few questions. > > How stable is the current API? Is it expected to change much? > > How stable is Erlyweb when running? I guess I expect minor issues > that can be worked around since it is new, but are there any larger > problems? What about yaws? > > I have noticed that many tutorials are from late 2006. Are these > still valid, or has it changed a lot since then? Can somebody > recommend a good tutorial? > > Are there any "live" Erlyweb sites out there today? > > If I can ask about yaws too, does it do SSL? > > Thanks. > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "erlyweb" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/erlyweb?hl=en -~----------~----~----~----~------~----~------~--~---
