From cb4f305ced5c36e28537a5fe9d03df22cd388ce9 Mon Sep 17 00:00:00 2001
From: messense <messense@icloud.com>
Date: Mon, 16 Jan 2023 10:04:00 +0800
Subject: [PATCH] Lock `stdout` once when printing diagnostics (#1901)

https://doc.rust-lang.org/stable/std/io/struct.Stdout.html

> Each handle shares a global buffer of data to be written to the standard output stream.
> Access is also synchronized via a lock and
> explicit control over locking is available via the [`lock`](https://doc.rust-lang.org/stable/std/io/struct.Stdout.html#method.lock) method.
---
 ruff_cli/src/printer.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/ruff_cli/src/printer.rs b/ruff_cli/src/printer.rs
index 4cd3542509..1ffe493f95 100644
--- a/ruff_cli/src/printer.rs
+++ b/ruff_cli/src/printer.rs
@@ -122,7 +122,7 @@ impl<'a> Printer<'a> {
         }
 
         if matches!(self.violations, Violations::Hide) {
-            let mut stdout = BufWriter::new(io::stdout());
+            let mut stdout = BufWriter::new(io::stdout().lock());
             if matches!(
                 self.format,
                 SerializationFormat::Text | SerializationFormat::Grouped
@@ -132,7 +132,7 @@ impl<'a> Printer<'a> {
             return Ok(());
         }
 
-        let mut stdout = BufWriter::new(io::stdout());
+        let mut stdout = BufWriter::new(io::stdout().lock());
         match self.format {
             SerializationFormat::Json => {
                 writeln!(
@@ -312,7 +312,7 @@ impl<'a> Printer<'a> {
             );
         }
 
-        let mut stdout = BufWriter::new(io::stdout());
+        let mut stdout = BufWriter::new(io::stdout().lock());
         if !diagnostics.messages.is_empty() {
             if self.log_level >= &LogLevel::Default {
                 writeln!(stdout)?;