Alex Xu

Generalist software developer

Education

Lassonde School of Engineering, B.Sc., Hons. Computer Science, York University, GPA: 7.7/9.0 (A).

Sept. 2016–May 2020:

Work

Ethica Channel Enablement Inc, Network Engineer.

Dec. 2018–Oct. 2019:

Developed several core projects and provided extensive consulting on C, Linux, git, and networking.

York University, Undergraduate Student Research Award researcher.

May–Aug. 2018:

Co-developed a Django web platform for worldwide crowdsourced hydrographic data collaboration.

York University, Teaching assistant.

June–July 2017:

Taught lab sessions for 48-student Android/web development course.

Community

Alpine Linux, Developer.

March 2020–present:

Reported, fully documented, and proposed fixes for many issues, including complex issues affecting many users such as clock_gettime64 EPERM in Docker, sh: write error: Invalid argument, and Raspberry Pi doesn't boot, 7 blinks. Proposed changes including compressing debuginfo and reconsidering -Os.

QEMU, Security researcher.

December 2020:

Discovered and reported an issue allowing full host device access from guests with virtiofsd enabled.

OpenJ9, Developer.

Aug.–Sept. 2020:

Collaborated to fix ISO C undefined behavior with misoptimization potential.

wfs, Developer.

June 2020:

Built a concurrent Python web font subsetter with automatic pixel-perfect verification.

cgit-syntax-highlighting, Developer.

March 2020:

Built a concurrent Python pygments microservice, reducing TTFB from 1.1s to 0.15s on cgit.alxu.ca. Improved portability and security and reduced LOC by 66% by switching from http.server to aiohttp.

Core Tor, Developer.

2017–present:

Contributed perf and flamegraphs profiles; optimized a hot loop from O(n2) with a malloc/free per item to O(n) with no allocs: c1, c2; and improved portability by integrating Rust cross-compile into autotools.

Linux kernel, Developer, Tester.

2012–present:

Diagnosed, reported, and fixed build, suspend, PCI, and other issues: lkml, linuxlists.

udpastcp, Developer.

July 2016:

Built a C tunnel to simulate datagrams using TCP packets, fixing TCP-over-TCP overhead.

Dwarf Therapist, Developer.

Aug. 2014–Sept. 2017:

Implemented cross-bit ptrace, migrated from qmake to CMake, and refactored code.

Simple Registry Editor, Developer.

Sept. 2008:

Built a minimal .NET registry editor.

Personal

Resume, Developer.

June 2020:

Rewrote my resume from LaTeX to modern web standards:

Skills

Alpine, Debian Linux; FreeBSD; Docker; Git; NGINX; WireGuard; TCP/IP; HTTP(S); DNS; SSH

Programming

C; C++; Go; Python; bash, POSIX sh; GNU make; HTML; CSS; JavaScript; SQL