Haozhun Jin
Member Of Technical Staff at OpenAI
Mountain View, California, United States
Summary
🤩
Rockstar🎓
Top SchoolHaozhun Jin is a seasoned backend software engineer with 13 years of experience building reliable, high-performance systems at major tech companies including Meta and currently OpenAI. He holds degrees from Tsinghua and Stanford in computer science and brings deep systems and compiler-level expertise, evidenced by contributions to the Hermes JavaScript engine and performance fixes in the Presto distributed SQL engine. Haozhun has a track record of shipping bug fixes, improving test reliability across platforms, and tuning query and HTTPS configurations for real-world production services. Based in Mountain View, he combines strong academic foundations with practical engineering at scale and a focus on correctness and security. An understated strength is his penchant for reducing subtle runtime failures—fixing out-of-bound accesses and cross-platform test issues that often evade typical QA.
13 years of coding experience
8 years of employment as a software developer
Bachelor's degree, Computer Science, Bachelor's degree, Computer Science at Tsinghua UniversityMaster's Degree, Computer Science, Master's Degree, Computer Science at Stanford University
Stackoverflow
6,441reputation
909kreached
62answers
33questions
ip-address
top-1%
java
top-5%
Github Skills (38)
algorithm10
algorithms10
ip-address10
javascript10
c-language10
query-builder10
testing10
http10
query-optimization10
data-structure10
java10
javas10
sql10
data-structures10
query-engine10
Programming languages (8)
Github contributions (5)
prestodb/presto
Feb 2015 - Dec 2018
The official home of the Presto distributed SQL query engine for big data
Role in this project:
Back-end Developer
Back-end DeveloperContributions:653 commits, 831 PRs, 419 pushes in 3 years 10 months
Contributions summary:Haozhun's contributions primarily focus on enhancing the Presto query engine. They implemented test cases for handling large BIGINT values and also improved query performance when using `IN` expressions with large constant lists. Additionally, the user addressed several bugs, including fixing data corruption and resolving issues related to handling time zones and column types in different scenarios.
distributed-sqlquerybigdataquery-enginesql
facebook/hermes
Jan 2019 - Apr 2020
A JavaScript engine optimized for running React Native.
Role in this project:Back-end Developer
Back-end DeveloperContributions:98 commits, 6 comments in 1 year 2 months
Contributions summary:Haozhun primarily contributed to the Hermes JavaScript engine, focusing on bug fixes, and performance improvements. They fixed out-of-bound vector access issues within the Regex compiler, and addressed LIT test failures on Windows, improving test reliability. The user also refactored the code by removing a mechanism for extra predefined strings. Furthermore, the user made several minor enhancements to the debugger.
javascript-enginereactreact-nativejavascriptoptimized
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