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log: stderr offending large log messages #4930

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Merged
algorandskiy merged 1 commit into from
Dec 22, 2022
Merged

log: stderr offending large log messages #4930

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11 changes: 11 additions & 0 deletions logging/cyclicWriter.go
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@ import (
"os"
"os/exec"
"path/filepath"
"runtime"
"strings"
"text/template"
"time"
Expand Down Expand Up @@ -124,6 +125,16 @@ func (cyclic *CyclicFileWriter) Write(p []byte) (n int, err error) {

if uint64(len(p)) > cyclic.limit {
// there's no hope for writing this entry to the log

// for the large lines this is a clear indication something does wrong, dump data into stderr
const minDebugLogLineSize = 10 * 1024 * 1024
if len(p) >= minDebugLogLineSize {
buf := make([]byte, 16*1024)
stlen := runtime.Stack(buf, false)
Comment on lines +132 to +133
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@cce cce Dec 21, 2022

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nit: debug.Stack() manages making a buffer for runtime.Stack() on your behalf, but 16K seems like it should be enough

10MB for min debug log line size is a lot!

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@algorandskiy algorandskiy Dec 21, 2022

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we get into this branch if exceeding cyclic.limit that is 1GB by default. and I only want to print really big messages even if someone sets smaller log file size for rotation.

fmt.Fprintf(os.Stderr, "Attempt to write a large log line:\n%s\n", string(buf[:stlen]))
fmt.Fprintf(os.Stderr, "The offending line:\n%s\n", string(p[:4096]))
}

return 0, fmt.Errorf("CyclicFileWriter: input too long to write. Len = %v", len(p))
}

Expand Down