Fix cuncurrent channel error (#202)

CHANGELOG.md

@@ -5,28 +5,39 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Fixed
+
+- Fixed deadlock when having high number of concurrent queries
+
 ## [0.14.0] - 2023-08-10
+
 ### Added
+
 - Support streaming for blob, for Managed client as well.
 - Support more urls for kusto, including http and port.
 
 ### Fixed
-  * Fixed wrong context deadline setting
-  * Fixed accepting empty url.
-
+
+* Fixed wrong context deadline setting
+* Fixed accepting empty url.
+
 ## [0.13.1] - 2023-05-24
 
 ### Changed
+
 - Modified `once.go` to reset `sync.Once` instance when an error occurs
 
 ## [0.13.0] - 2023-05-09
 
 ### Added
 
 - `ServerTimeout` Query Option
-  - The timeout to the server will be set to the value of this option, or to none if `RequestNoTimeout` is set to true.
-  - If it is not provided, the timeout will be set by the context (the old behaviour).
-  - If a context timeout is not provided, it will fall back to a default value by the type of request.
+    - The timeout to the server will be set to the value of this option, or to none if `RequestNoTimeout` is set to
+      true.
+    - If it is not provided, the timeout will be set by the context (the old behaviour).
+    - If a context timeout is not provided, it will fall back to a default value by the type of request.
 - Support for `IgnoreFirstRecord` ingestion option
 
 ### Changed

kusto/reader.go

@@ -92,15 +92,19 @@ func newRowIterator(ctx context.Context, cancel context.CancelFunc, execResp exe
 		RequestHeader:  execResp.reqHeader,
 		ResponseHeader: execResp.respHeader,
 
-		op:           op,
-		ctx:          ctx,
-		cancel:       cancel,
-		progressive:  header.IsProgressive,
-		inColumns:    make(chan send, 1),
+		op:          op,
+		ctx:         ctx,
+		cancel:      cancel,
+		progressive: header.IsProgressive,
+		// There could be a case where the rows channel fires before the columns channel
+		// So now the rows channel assumes the columns have been recieved, but the loop on the other side is blocked.
+		// Raising the buffer size solves this issue in practice - since inColumns never has to wait, it always compeletes first.
+		// This isn't a perfect solution, but this code is going to be discarded for v2 anyway.
+		inColumns:    make(chan send, 5),
 		inRows:       make(chan send, 100),
-		inProgress:   make(chan send, 1),
-		inNonPrimary: make(chan send, 1),
-		inCompletion: make(chan send, 1),
+		inProgress:   make(chan send, 5),
+		inNonPrimary: make(chan send, 5),
+		inCompletion: make(chan send, 5),
 		inErr:        make(chan send),
 
 		rows:       make(chan Row, 1000),