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

March 2020–present:

Reported, documented, and contributed fixes for issues including Operation not permitted in Docker, sh: write error: Invalid argument, and Raspberry Pi doesn't boot, 7 blinks. Proposed changes including -fno-plt for x86 and x86_64, compressing debuginfo, and reconsidering -Os.

libglvnd

September 2021:

Implemented correct global-dynamic TLS support, fixing musl compatibility.

Wine

July 2021:

Implemented copy_file_range support, shrinking Wine prefixes from 200 MB to less than 1 MB.

Linux kernel

2012–present:

Reported issues and submitted fixes: lkml, linuxlists. Diagnosed Cargo issue 9739 to a long-standing kernel bug, and fixed the underlying issue, resolving a deadlock in GNU Make and similar jobservers.

QEMU

December 2020:

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

wfs

June 2020:

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

cgit-syntax-highlighting

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.

udpastcp

July 2016:

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

Dwarf Therapist

Aug. 2014–Sept. 2017:

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

Simple Registry Editor

Sept. 2008:

Built a minimal .NET registry editor.

Personal

Resume

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