What version of Go are you using (go version)?

$ go version
go version go1.19.9 linux/arm64

Does this issue reproduce with the latest release?

This issue appears sporadically and a consistent method of reproduction has not yet been identified.

What operating system and processor architecture are you using (go env)?

$ go env
GO111MODULE=""
GOARCH="arm64"
GOBIN=""
GOCACHE="/root/.cache/go-build"
GOENV="/root/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_arm64"
GOVCS=""
GOVERSION="go1.19.9"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/dev/null"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -pthread -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build3855752231=/tmp/go-build -gno-record-gcc-switches"

What did you do?

We're building our server application using the golang:1.19-alpine3.17 Docker image and running it on alpine:3.17, as outlined in the attached Dockerfile:

# syntax=docker/dockerfile:1
FROM golang:1.19-alpine3.17 AS builder
RUN apk add --update --no-cache gcc g++ make git openssh-client \
  && mkdir -p -m 0600 ~/.ssh \
  && ssh-keyscan github.com >> ~/.ssh/known_hosts \
  && git config --global url."git@github.com:XXXXX/".insteadOf "https://github.com/XXXXX/" \
  && go env -w GOPRIVATE=github.com/XXXXX
WORKDIR /app
COPY ./go.mod ./go.sum ./Makefile ./
RUN --mount=type=ssh make init -o init-lint
COPY ./ ./
RUN make -o init

FROM alpine:3.17
ENV TZ=XXXXX
RUN apk add --update --no-cache ca-certificates tzdata \
  && cp /usr/share/zoneinfo/$TZ /etc/localtime \
  && echo $TZ > /etc/timezone
WORKDIR /app
COPY --from=builder /app/bin/ ./
COPY ./configs/ ./configs/
CMD ["./XXXXX"]
EXPOSE 80

The application is an HTTP server based on gin v1.7.7, handling an average of 1K RPM (requests per minute) per container in our AWS EKS setup.

Our deployment includes liveness and readiness health checkers on each pod. These checkers execute simple HTTP requests and expect a 200 OK response. This HTTP request invokes a basic handler logic that returns a 200 OK status without any business-related processing. Of course, the application also has numerous endpoints for actual business operations.

Issue Description

Since May 31, we've encountered an error serveral times, evidenced by the attached stacktrace.

*runtime.TypeAssertionError: interface conversion: interface {} is , not chan struct {}
  File "/go/pkg/mod/github.com/XXXXX/XXXXX@v1.0.25/pkg/httpserver/middleware/sentry.go", line 58, in Sentry.func1.1.1
  File "/usr/local/go/src/context/context.go", line 361, in (*cancelCtx).Done
  File "/go/pkg/mod/github.com/XXXXX/XXXXX@v1.0.25/pkg/httpserver/middleware/timeout.go", line 81, in Timeout.func2.1
  File "/go/pkg/mod/github.com/XXXXX/XXXXX@v1.0.25/pkg/httpserver/middleware/sentry.go", line 75, in Sentry.func1.1
  File "/go/pkg/mod/github.com/XXXXX/XXXXX@v1.0.25/pkg/httpserver/middleware/recovery.go", line 23, in Recovery.func1.1
  File "/go/pkg/mod/github.com/XXXXX/XXXXX@v1.0.25/pkg/httpserver/middleware/wraperror.go", line 17, in WrapError.func1.1
  File "/go/pkg/mod/github.com/XXXXX/XXXXX@v1.0.25/pkg/httpserver/middleware/logging.go", line 28, in AccessLogging.func1.1.1
  File "/go/pkg/mod/github.com/XXXXX/XXXXX@v1.0.25/pkg/util/timeutil/timeutil.go", line 41, in Process
  File "/go/pkg/mod/github.com/XXXXX/XXXXX@v1.0.25/pkg/httpserver/middleware/logging.go", line 27, in AccessLogging.func1.1
  File "/go/pkg/mod/github.com/XXXXX/XXXXX@v1.0.25/pkg/httpserver/ginrouter/ginrouter.go", line 242, in (*ginRouter).toGinHandler.func1
  File "/go/pkg/mod/github.com/gin-gonic/gin@v1.7.7/context.go", line 168, in (*Context).Next
  File "/go/pkg/mod/github.com/gin-contrib/gzip@v0.0.3/handler.go", line 60, in (*gzipHandler).Handle
  File "/go/pkg/mod/github.com/gin-gonic/gin@v1.7.7/context.go", line 168, in (*Context).Next
  File "/go/pkg/mod/github.com/gin-gonic/gin@v1.7.7/gin.go", line 555, in (*Engine).handleHTTPRequest
  File "/go/pkg/mod/github.com/gin-gonic/gin@v1.7.7/gin.go", line 511, in (*Engine).ServeHTTP
  File "/usr/local/go/src/net/http/server.go", line 2947, in serverHandler.ServeHTTP
  File "/usr/local/go/src/net/http/server.go", line 1991, in (*conn).serve

This specific error occurred on four seperate occasions: May 31, Jun 4, Jun 5, and Jun 8.
(Note that the docker image we're using updated golang version to 1.19.9 on May 3, and then to 1.19.10 on Jun 7, but Jun 8 case was using 1.19.9 yet)

Importantly, all four instances of this panic occurred while processing the health check endpoint.

The root of the panic seems to originate from the code found at File "/usr/local/go/src/context/context.go", line 361:

func (c *cancelCtx) Done() <-chan struct{} {
	d := c.done.Load()
	if d != nil {
		return d.(chan struct{}) // !!Line 361!!
	}
	c.mu.Lock()
	defer c.mu.Unlock()
	d = c.done.Load()
	if d == nil {
		d = make(chan struct{})
		c.done.Store(d)
	}
	return d.(chan struct{})
}

But we have not yet determined why this type conversion cannot be done.

And, the most interesting part is the panic message:

*runtime.TypeAssertionError: interface conversion: interface {} is , not chan struct {}

The actual type of the interface {} is not specified in the message - it merely appears as an empty string between is and ,.

As this panic occurs only sporadically and is not currently reproducible, we're seeking insights from anyone who might have experienced a similar issue. If additional information is required for debugging, let us know what further data we can collect from our production application and how to get it.