So I guess SLAMD is a thing again…

The year was 2002. I had recently jumped ship from Netscape to Sun Microsystems after AOL bought Netscape and decided they wanted out of their iPlanet alliance. I was working as a sustaining engineer on whatever Sun’s brilliant marketeers decided to call their LDAP directory server at the time. One day, my boss, Steve Shoaff, came into my office with a couple of ideas. He said that he wanted me to build a tool that could measure the directory server performance with a lot of load by hitting it from multiple clients at the same time. And he said that he wanted to call it “SLAMD”, which is a play on “slapd”, which kind of stands for “standalone LDAP daemon” and is used in the process names of some directory server products.

So I built it, and I think that it’s fair to say that it turned into something substantially more impressive than either of us originally imagined. It had a Java-based API that you could use to define the types of workloads that you wanted to process, a web-based interface that you could use to schedule jobs and view the results (numerically and graphically), and a client that you could install on the systems that you wanted to used to drive load against the server. Over time, I added new types of jobs and lots of other features, like self-optimizing jobs (which repeatedly run the same job with different amounts of client load to find the optimal performance), job groups (which let you schedule several jobs to run in succession), and resource monitoring (which lets you monitor system statistics like CPU, disk, and network utilization on various systems).

SLAMD was pretty good at what it did, and it worked with all types of LDAP-compliant directory servers, so it became one of the preeminent directory server benchmarking tools. We convinced Sun to open source it, and lots of people started using it. It could be used for things other than directory servers, too (I did build some basic support for other protocols like HTTP, POP3, IMAP, and SMTP, and the ability to interact with relational databases), but LDAP performance and stress testing was always its big wheelhouse.

Fast forward several years, and SLAMD was still pretty great but was starting to show its age, at least under the covers. I started working on it in the Java 1.3 days, before nice features like generics, foreach, concurrency APIs, sub-millisecond timing, and so much more. The web interface was all hand-crafted HTML and mostly contained in one giant source file, and it was getting pretty unwieldy. I did make some attempts to try to modernize it, but I got really busy with other things, like creating OpenDS as a replacement for Sun’s stagnating C-based directory server, then moving on from Sun to launch UnboundID and working furiously to build up its directory server, directory proxy server, and LDAP SDK products.

Shortly after Sun and I parted ways, Oracle bought Sun and gradually started killing off most of the good things about it. This included shutting down the site, which had been the open source repository for SLAMD, and I decided to take that opportunity to just let it kind of fade away. I figured it might be better to start something new from scratch, with a much more modern foundation, than to try to give SLAMD the kind of makeover I thought it needed. Of course, that was nearly a decade ago, and while I’ve done a lot since then, creating a new directory server benchmarking tool (other than a handful of command-line tools like searchrate and modrate that we ship with the LDAP SDK) hasn’t really been in the cards. Meanwhile, SLAMD is still getting a surprising amount of use. Even though it’s not so easy to get your hands on it anymore, people were still getting their hands on it and using it.

After having the topic come up several times in the last few weeks, I finally bit the bullet and dusted off the old code. I spent a couple of weekends doing some pretty extensive code cleanup. I fully generified everything, so there aren’t any more build warnings about raw types. I pulled in much more modern versions of dependencies like Apache Tomcat, the Berkeley DB Java Edition, and the UnboundID LDAP SDK for Java. I reorganized some of the jobs, including putting some legacy stuff out to pasture, and I wrote new versions of several of them. I split up some of the admin interface code into separate source files to make it more manageable, and I made some minor user interface enhancements.

So anyway, I went ahead and put the updated code on GitHub at Since no single entity owns the copyright on the code, it’s not possible to change the license, and it will therefore always will be licensed under the terms of the Sun Public License version 1.0. I’m not promising that I’ll add any major new features, but it’ll at least be more readily available than it has been, and with some more modern guts.

For now, if you want to use it, you’ll need to check it out and build it for yourself (there’s a README that tells you how to do that). Just know that it’s not backward-compatible with the version that I last touched in 2010, so don’t try to upgrade an existing instance (but if you do want the code for that old version, just check out revision 5777f3e5d78ff03985af4e68670e649127339c59, since I used it to seed the new repository).

Also note that there’s still a lot more work to do. There’s quite a bit more code cleanup that’s still on my to-do list (it builds cleanly with Java 8, but there are several deprecation warnings with Java 11). I plan on rewriting some more of the jobs (including making some potentially-incompatible changes). I know that some of the resource monitoring is broken (at least on Linux, which isn’t so concerned about maintaining consistent output in some of its commands). I haven’t touched any of the documentation. I’ve only done a very minimal amount of testing so far. So while it’s fine to play around with what’s there now, and please report issues if you find them, just know that I reserve the right to make even more non-backward-compatible changes as I continue to modernize the code.