Fix memory usage issues.

contrib/pzstd/utils/WorkQueue.h

@@ -99,6 +99,19 @@ class WorkQueue {
     return true;
   }
 
+  /**
+   * Sets the maximum queue size.  If `maxSize == 0` then it is unbounded.
+   *
+   * @param maxSize The new maximum queue size.
+   */
+  void setMaxSize(std::size_t maxSize) {
+    {
+      std::lock_guard<std::mutex> lock(mutex_);
+      maxSize_ = maxSize;
+    }
+    writerCv_.notify_all();
+  }
+
   /**
    * Promise that `push()` won't be called again, so once the queue is empty
    * there will never any more work.
@@ -149,6 +162,10 @@ class BufferWorkQueue {
     return result;
   }
 
+  void setMaxSize(std::size_t maxSize) {
+    queue_.setMaxSize(maxSize);
+  }
+
   void finish() {
     queue_.finish();
   }