Fix max_open_files throttle threshold

Rafał Hibner · Rafał Hibner · commit aaeefd893cac · 2025-05-13T08:03:51.000Z
diff --git a/cpp/src/arrow/dataset/dataset_writer.cc b/cpp/src/arrow/dataset/dataset_writer.cc
@@ -58,7 +58,7 @@ class Throttle {
       return Future<>::MakeFinished();
     }
     std::lock_guard<std::mutex> lg(mutex_);
-    if (current_value_ > max_value_) {
+    if (current_value_ >= max_value_) {
       in_waiting_ = values;
       backpressure_ = Future<>::Make();
     } else {
@@ -75,7 +75,7 @@ class Throttle {
     {
       std::lock_guard<std::mutex> lg(mutex_);
       current_value_ -= values;
-      if (in_waiting_ > 0 && current_value_ <= max_value_) {
+      if (in_waiting_ > 0 && current_value_ < max_value_) {
         in_waiting_ = 0;
         to_complete = backpressure_;
       }

Original file line number	Diff line number	Diff line change
`@@ -58,7 +58,7 @@ class Throttle {`
`58`	`58`	`return Future<>::MakeFinished();`
`59`	`59`	`}`
`60`	`60`	`std::lock_guard<std::mutex> lg(mutex_);`
`61`		`- if (current_value_ > max_value_) {`
	`61`	`+ if (current_value_ >= max_value_) {`
`62`	`62`	`in_waiting_ = values;`
`63`	`63`	`backpressure_ = Future<>::Make();`
`64`	`64`	`} else {`
`@@ -75,7 +75,7 @@ class Throttle {`
`75`	`75`	`{`
`76`	`76`	`std::lock_guard<std::mutex> lg(mutex_);`
`77`	`77`	`current_value_ -= values;`
`78`		`- if (in_waiting_ > 0 && current_value_ <= max_value_) {`
	`78`	`+ if (in_waiting_ > 0 && current_value_ < max_value_) {`
`79`	`79`	`in_waiting_ = 0;`
`80`	`80`	`to_complete = backpressure_;`
`81`	`81`	`}`