  Go is a modern programming language gaining popularity in enterprise
microservice systems. Concurrency is a first-class citizen in Go with
lightweight ``goroutines'' as the building blocks of concurrent execution. Go
advocates message-passing to communicate and synchronize among goroutines.
Improper use of message passing in Go can result in ``partial deadlocks'' , a
subtle concurrency bug where a blocked sender (receiver) never finds a
corresponding receiver (sender), causing the blocked goroutine to leak memory,
via its call stack and objects reachable from the stack.
  In this paper, we systematically study the prevalence of message passing and
the resulting partial deadlocks in 75 million lines of Uber's Go monorepo
hosting over 2500 microservices. We develop two lightweight, dynamic analysis
tools: Goleak and LeakProf, designed to identify partial deadlocks. Goleak
detects partial deadlocks during unit testing and prevents the introduction of
new bugs. Conversely, LeakProf uses goroutine profiles obtained from services
deployed in production to pinpoint intricate bugs arising from complex control
flow, unexplored interleavings, or the absence of test coverage. We share our
experience and insights deploying these tools in developer workflows in a large
industrial setting. Using Goleak we unearthed 857 pre-existing goroutine leaks
in the legacy code and prevented the introduction of around 260 new leaks over
one year period. Using LeakProf we found 24 and fixed 21 goroutine leaks, which
resulted in up to 34% speedup and 9.2x memory reduction in some of our
production services.
