From 0c1ac953b93939db23d1cc3b6eaa8d4df7863552 Mon Sep 17 00:00:00 2001
From: ChristopherDedominici
 <18092467+ChristopherDedominici@users.noreply.github.com>
Date: Thu, 12 Feb 2026 16:04:57 +0000
Subject: [PATCH 1/2] allow multiple parallel downloads of different compilers

---
 .../solidity/build-system/compiler/downloader.ts   | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/v-next/hardhat/src/internal/builtin-plugins/solidity/build-system/compiler/downloader.ts b/v-next/hardhat/src/internal/builtin-plugins/solidity/build-system/compiler/downloader.ts
index 191d48ff226..ae4d7014395 100644
--- a/v-next/hardhat/src/internal/builtin-plugins/solidity/build-system/compiler/downloader.ts
+++ b/v-next/hardhat/src/internal/builtin-plugins/solidity/build-system/compiler/downloader.ts
@@ -153,7 +153,6 @@ export class CompilerDownloaderImplementation implements CompilerDownloader {
   readonly #compilersDir: string;
   readonly #downloadFunction: typeof download;
 
-  readonly #mutexCompiler = new MultiProcessMutex("compiler-download");
   readonly #mutexCompilerList = new MultiProcessMutex("compiler-download-list");
 
   /**
@@ -200,11 +199,14 @@ export class CompilerDownloaderImplementation implements CompilerDownloader {
   }
 
   public async downloadCompiler(version: string): Promise<boolean> {
-    // Since only one process at a time can acquire the mutex, we avoid the risk of downloading the same compiler multiple times.
-    // This is because the mutex blocks access until a compiler has been fully downloaded, preventing any new process
-    // from checking whether that version of the compiler exists. Without mutex it might incorrectly
-    // return false, indicating that the compiler isn't present, even though it is currently being downloaded.
-    return this.#mutexCompiler.use(async () => {
+    // A per-version mutex ensures that only one process at a time can download a given compiler version,
+    // while still allowing different compiler versions to be downloaded in parallel.
+    // Without the mutex, a concurrent process might check whether a version exists, incorrectly
+    // find it missing (because another process is still downloading it), and start a redundant download.
+
+    const mutex = new MultiProcessMutex(`compiler-download-${version}`);
+
+    return mutex.use(async () => {
       const isCompilerDownloaded = await this.isCompilerDownloaded(version);
 
       if (isCompilerDownloaded === true) {

From 78af2ed546ad5a0bafa44785e275855d6876530d Mon Sep 17 00:00:00 2001
From: Christopher Dedominici
 <18092467+ChristopherDedominici@users.noreply.github.com>
Date: Thu, 12 Feb 2026 17:08:56 +0100
Subject: [PATCH 2/2] Create sweet-seas-shake.md

---
 .changeset/sweet-seas-shake.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/sweet-seas-shake.md

diff --git a/.changeset/sweet-seas-shake.md b/.changeset/sweet-seas-shake.md
new file mode 100644
index 00000000000..231659261cc
--- /dev/null
+++ b/.changeset/sweet-seas-shake.md
@@ -0,0 +1,5 @@
+---
+"hardhat": patch
+---
+
+Allow multiple parallel downloads of different compilers ([7946](https://github.com/NomicFoundation/hardhat/pull/7946)).