Alfred Perlstein - Résumé Contact Information: Alfred Perlstein San Francisco, CA Email: alfred at freebsd dot org URL: http://freebsd.org/~alfred/ Professional Objective: Seeking challenging technical position as an architect in software development dealing with operating system programming, scalable internet applications or systems operation, preferably on FreeBSD based UNIX systems. Highly adaptive and experienced kernel programmer and UNIX system administrator with management experience. Experienced in distributed computation, low level programming, optimization and device driver programming. Expertise programming with C, C++, shell, perl and python in the UNIX environment. Languages:: C (Unix and PC environment 10+ years) (expert), UNIX shell programming (sh/zsh) (10+ years) (expert), C++ (OOP/STL) (7 years) (expert), Perl (highly skilled), SQL, php, 80x86 Assembly (MS-DOS), Python, Ruby+Rails, basic HTML. Development tools:: make (Berkeley and GNU) (expert), CVS (highly skilled), gprof (highly skilled), lex/flex, yacc/bison, GDB, Subversion, Valgrind, Purify, Coverity. Development environments:: FreeBSD (expert), OS X (highly skilled), Redhat Linux. System administration: FreeBSD (expert), NetBSD, OpenBSD, SGI IRIX 6.x, Sun Solaris (sparc/x86: 2.6), Sun-OS 4.1.1, Redhat Linux. Protocol and driver knowledge: TCP/IP (expert), UDP (expert), NFS (expert), RPC (expert), HTTP, FTP, SMTP, Ethernet Drivers. Employment History: BSD Kernel Programmer Juniper Networks January 2007-August 2010 Responsible for scaling JUNOS (FreeBSD based OS) to a 32 processor router blade. FreeBSD Liason. Ported cutting edge FreeBSD features to in-house version of OS. Projects: * Scaling work: Added a reader/writer lock over the JUNOS networking stack to allow multiple networking flows to run in parallel. Achieved 5x speedup when processor was configured with 8 cores. Required back porting of FreeBSD 7.x rwlocks to FreeBSD 6 including turnstiles and sx locks and rwlocks. Required adding writer priority to the FreeBSD rwlocks. User space critical sections to prevent latency when contending against spin locks on cores running real-time processes. Flow affinity. Network processor pins flows to particular CPUs. By exporting this information to user space applications can exhibit much better cache and locking effects by assigning flows to threads already bound to the same CPU. * FreeBSD liaison: Take non-core intellectual property modifications to FreeBSD and add them to FreeBSD to ease further upgrades of our code base. Recruited several strong FreeBSD developers into Juniper. * Subversion deployment: Setup CVS to subversion gateway for team members to have branches. System tracked our CVS top of tree by committing to Subversion. * Warlock: Created a tool to assist developer check-in of code. Reduced number of build breaks by using this tool to 0%. Saves developers many hours per-day by streamlining and pipelining the commit process for the common case. Nominated for distinguished tool of the year. CTO Humor Rainbow Inc, OkCupid.com July 2005-August 2006 Chief technical officer. Responsible for all technical aspects of Okcupid's direction. Duties included managing the software team (3 developers), recruiting, data center management and deployment, office deployment, release engineering, source control, UNIX administration and developing code. Responsible for software development and web site uptime. Projects: * Match server: Created an linearly scalable system to replace a failure prone and non-scalable solution. Using two servers (but scalable to the hundreds) I fit a large subset of the users into physical ram using a custom R-star tree to locate users that are adjacent. Additionally a distributed cache (modeled after the memcached project) was modified to allow for distributed computation of match results. This system replaced a mysql backed system and was able to perform a better job using half the hardware of the old system at a fraction of the complexity and maintenance of the old system. Additionally this system allowed for "fast path" access for several important data points for users. * Image server migration and reliability: Our image servers were located at a separate hosting facility. Reliability problems at the hosting facility prompted me to move the machines to our local co-location facility. To maximize reliability, once the servers were made local, they were put behind a load balancer and made 100% redundant. Prior to this work, if an image server went down we lost images on the site until a manual switch over was done. Achievements: * Engineered a number of improvements to key services and monitoring systems such that the number of incidents has gone from multiple incidents per week to less than one incident per month. * Created bidding war between ISPs which allowed us to get three free months of 40 megabit egress and reduced our hosting costs to less than half. FreeBSD committer FreeBSD August 1999- Authorized to add/change code in the FreeBSD operating system. Projects: * Autofs implementation: Completed a filesystem that supports dispatch of kernel filesystem operations to user land to facilitate dynamic browsing. This facilitates user land direction of the kernel policy presented to VFS consumers. * Working on bug fixes and SMP support. Interests include NFS performance, software RAID, Symmetric Multiprocessing (SMP), the Linux emulator, kernel vm/buffer-cache, network subsystems and threads libraries. * Assisted in the design of the multiprocessor safe (MP safe) network buffer allocator, currently working on making the socket subsystem MP safe. * Made file allocation subsystem MP safe, collaborated with other FreeBSD developers (Seigo Tanimura in particular) to accomplish this. * Ported BSD/os client side NFS locking implementation to FreeBSD. Included both user space and kernel subsystems. * Added support for PCI based wireless cards based on the Prism/Prism2 chipsets. * Modularized several large subsystems including the System V IPC subsystem and the POSIX aio subsystem by converting them to loadable kernel modules. * PXE step-by-step guide to network booting FreeBSD systems for install or lab deployment. Presented work at Google (http://www.google.com) and Jarna (http://www.jarna.com/) . Project is available at http://people.freebsd.org/~alfred/pxe . * Integrated and improved Yahoo! ( http://www.yahoo.com ) 'accept filter' kernel technology into FreeBSD. * Ported pthread cancel functionality from OpenBSD Technical Yahoo Yahoo Inc. April 2004-April 2005 Senior technical Yahoo. Responsible for search operations and optimization. Projects: * Session Server. A distributed database that stores key/value pairs in a highly replicated manner. Data is stored on multiple backends and the information needed to retrieve said data is made available to clients. Multiple machine failures do not impact the availability of data. Nodes participating in data storage are automatically detected via broadcast. Project included custom thread safe RPC server dispatch stubs and quorum logic. * DNS Cache. A local cache for DNS requests designed to reduce the impact of latency and down time of DNS servers. * Companion servers. A system for providing web ranks for users of the Yahoo toolbar. Optimized data build process from five days down to ten hours. Optimized lookup by storing data in binary format, tuning database cache size, splitting databases into multiple buckets. Tuned database build turaround from one week to ten hours. * Invariants class. A C++ class developed in order to track down bugs in code. Utilized inheritance to provide all derived classes with checkpoints in order to ensure object coherence. Provided mechanisms for identifying corruption and memory leaks at runtime with negligible performance impact. * Apache data bridge module. Created an apache module that made passing data between our core components and third party developer code simple. Greatly reduced the complexity required of third party developers interfacing with our code. Kernel developer, contractor Apple Computer Inc. November 2002-March 2004 Tasked with enhancing and fixing Apple Computer's OS X operating system implementation of NFS. Tasked with creating the AutoFS filesystem for Apple Computer. Projects: * Main role assigned to enhance the experience of mobile users of NFS. This involved debugging several aspects of the NFS component mostly related to networking and process management. * Provided implementation of autofs for OS X. * Provided general filesystem notification mechanism for signaling filesystem alerts such as loss of connection to server, low disk space, filesystem mount and unmount. OS X is now the only UNIX based system to provide an escape mechanism for a broken NFS mount. * Debugging, fixing and providing peer review to address issues. (example: forceful unmount of NFS filesystems.) Contractor Self. March 2001-November 2002 Worked at several companies on performance tuning and operating system development. Principal Technologist Wintelcom March 1999-March 2001 Senior Architect, Programmer, Systems administrator, on call 24/7. Projects: * Lead designer of distributed high performance web tracking system. Project utilized C, Perl, SQL, PHP and FreeBSD. * System administration, on call 24/7. Systems include high traffic web servers, DNS (bind 8), and NFS on platforms; FreeBSD (2.2.x/3.x/4.0), Sun Solaris (2.6/7) and Redhat Linux. * Maintaining systems and source code via CVS. * Designed an interpreter used to increase page rankings for web pages. * Maintained systems consisting of databases (My-SQL, Postgresql), Perl, php and sh scripts. Responsible for backups, system security and bandwidth monitoring. * Modified Postgresql client libraries to provide nonblocking support for C client code. (integrated in mainstream sources) * Added support to pre-load data into the FreeBSD kernel to support zero copy data transport. Achieved *2500* connections per-second on a single 400mhz PII. * Building x86 and Sun Ultra-sparc systems using FreeBSD and Solaris for internal and customer use. * Tuning FreeBSD systems to support large Postgresql and Apache installs. Education: BA in Computer Science, July 1998. Attended, left before graduation for position at Hot Jobs Inc. SUNY Tech at Utica/Rome HS, July 1994 Stuyvesant HS, New York, NY Hobbies: * Development of FreeBSD kernel (network/filesystem) and userland. * Skiing. * Motorcycling, Vmax, zx10, gs500, Elite 250 scooter, I ride and do my own bike maintence. Miscellany: Written using vim http://www.vim.org/ using the xml suite xmlresume available at http://xmlresume.sourceforge.net/ . Last modified May 2011.