diff --git a/pluto/src/pluto/memory_resource/MemoryPoolResource.cc b/pluto/src/pluto/memory_resource/MemoryPoolResource.cc
index 00284803a..1198bc7bb 100644
--- a/pluto/src/pluto/memory_resource/MemoryPoolResource.cc
+++ b/pluto/src/pluto/memory_resource/MemoryPoolResource.cc
@@ -39,6 +39,20 @@ static std::size_t to_bytes(const std::string& str) {
     return std::stoull(str);
 }
 
+static std::string bytes_to_string(std::size_t bytes) {
+    std::string str;
+    constexpr std::size_t MB = 1024*1024;
+    constexpr std::size_t GB = 1024*MB;
+    if( bytes >= GB ) {
+        str = std::to_string(bytes/GB) + "GB";
+    }
+    else {
+        str = std::to_string(bytes/MB) + "MB";
+    }
+    return str;
+}
+
+
 static pool_options default_pool_options_;
 static bool default_pool_options_setup_ = false;
 
@@ -60,6 +74,51 @@ void set_default_pool_options(pool_options options) {
     default_pool_options_setup_ = true;
 }
 
+static GatorMemoryResource* to_gator_resource(memory_resource* pool) {
+    GatorMemoryResource* gator;
+    if (TraceMemoryResource* traced = dynamic_cast<TraceMemoryResource*>(pool)) {
+        gator = dynamic_cast<GatorMemoryResource*>(traced->upstream_resource());
+    }
+    else {
+        gator = dynamic_cast<GatorMemoryResource*>(pool);
+    }
+    return gator;
+}
+
+void* MemoryPoolResource::do_allocate(std::size_t bytes, std::size_t alignment) {
+    std::lock_guard lock(mtx_);
+    return resource(bytes)->allocate(bytes, alignment);
+}
+
+void MemoryPoolResource::do_deallocate(void* ptr, std::size_t bytes, std::size_t alignment) {
+    std::lock_guard lock(mtx_);
+    if (pools_.size() == 1) {
+        pools_[0]->deallocate(ptr, bytes, alignment);
+    }
+    else {
+        for (int i=0; i<pool_block_sizes_.size(); ++i) {
+            if (pools_[i]) {
+                auto& gator = to_gator_resource(pools_[i].get())->gator();
+                if (gator.thisIsMyPointer(ptr)) {
+                    pools_[i]->deallocate(ptr, bytes, alignment);
+                }
+
+                // Cleanup empty gator when a larger gator exists
+                if (gator.get_bytes_currently_allocated() == 0 && pool_block_size_ > pool_block_sizes_[i]) {
+#if PLUTO_DEBUGGING
+                std::cout << " - Releasing memory_pool["<<i<<"] with block_size " << bytes_to_string(pool_block_sizes_[i]) << " and capacity " << bytes_to_string(gator.get_pool_capacity()) << std::endl;
+#endif
+                    pools_[i].reset();
+                }
+            }
+        }
+    }
+}
+
+bool MemoryPoolResource::do_is_equal(const memory_resource& other) const noexcept {
+    if (this == &other) { return true; }
+    return false;
+}
 
 memory_resource* MemoryPoolResource::resource(std::size_t bytes) {
     constexpr std::size_t MB = 1024*1024;
@@ -91,15 +150,8 @@ memory_resource* MemoryPoolResource::resource(std::size_t bytes) {
         options.initial_size = blocks_per_chunk*pool_block_size_;
         options.grow_size    = blocks_per_chunk*pool_block_size_;
         if (TraceOptions::instance().enabled) {
-            std::string size_str;
-            if( pool_block_size_ >= GB ) {
-                size_str = std::to_string(pool_block_size_/GB) +"GB"; 
-            }
-            else {
-                size_str = std::to_string(pool_block_size_/MB) +"MB"; 
-            }
             pools_[pool_index] =
-                std::make_unique<TraceMemoryResource>("gator["+size_str+"]",
+                std::make_unique<TraceMemoryResource>("gator["+bytes_to_string(pool_block_size_)+"]",
                 std::make_unique<GatorMemoryResource>(options, upstream_) );
         }
         else {
@@ -110,30 +162,8 @@ memory_resource* MemoryPoolResource::resource(std::size_t bytes) {
     return pool_;
 }
 
-static GatorMemoryResource* to_gator_resource(memory_resource* pool) {
-    GatorMemoryResource* gator;
-    if (TraceMemoryResource* traced = dynamic_cast<TraceMemoryResource*>(pool)) {
-        gator = dynamic_cast<GatorMemoryResource*>(traced->upstream_resource());
-    }
-    else {
-        gator = dynamic_cast<GatorMemoryResource*>(pool);
-    }
-    return gator;
-}
-
-void MemoryPoolResource::cleanup_unused_gators() {
-    for (int i=0; i<pool_block_sizes_.size(); ++i) {
-        if (pools_[i] && pool_block_size_ > pool_block_sizes_[i]) {
-#if PLUTO_DEBUGGING
-            auto& gator = to_gator_resource(pools_[i].get())->gator();
-            std::cout << " - Releasing memory_pool["<<i<<"] with block_size " << pool_block_sizes_[i] << " and capacity " << gator.get_pool_capacity() << std::endl;
-#endif
-            pools_[i].reset();
-        }
-    }
-}
-
 std::size_t MemoryPoolResource::size() const {
+    std::lock_guard lock(mtx_);
     std::size_t _size{0};
     for (const auto& pool: pools_) {
         if (pool) {
@@ -147,6 +177,7 @@ std::size_t MemoryPoolResource::size() const {
 }
 
 std::size_t MemoryPoolResource::capacity() const {
+    std::lock_guard lock(mtx_);
     std::size_t _capacity{0};
     for (const auto& pool: pools_) {
         if (pool) {
diff --git a/pluto/src/pluto/memory_resource/MemoryPoolResource.h b/pluto/src/pluto/memory_resource/MemoryPoolResource.h
index 50e9188c1..abfe707f3 100644
--- a/pluto/src/pluto/memory_resource/MemoryPoolResource.h
+++ b/pluto/src/pluto/memory_resource/MemoryPoolResource.h
@@ -11,6 +11,7 @@
 
 #include <memory>
 #include <vector>
+#include <mutex>
 
 #include "pluto/memory_resource/memory_resource.h"
 
@@ -44,6 +45,7 @@ class MemoryPoolResource : public memory_pool_resource {
 	}
 
 	void release() override {
+		std::lock_guard lock(mtx_);
 		pools_.clear();
 	}
 
@@ -60,26 +62,13 @@ class MemoryPoolResource : public memory_pool_resource {
 	}
 
 protected:
-    void* do_allocate(std::size_t bytes, std::size_t alignment) override {
-		return resource(bytes)->allocate(bytes, alignment);
-    }
+    void* do_allocate(std::size_t bytes, std::size_t alignment) override;
+    void do_deallocate(void* ptr, std::size_t bytes, std::size_t alignment) override;
+    bool do_is_equal(const memory_resource& other) const noexcept override;
 
-    void do_deallocate(void* ptr, std::size_t bytes, std::size_t alignment) override {
-		resource(bytes)->deallocate(ptr, bytes, alignment);
-		// possible to cleanup no longer used gators
-		cleanup_unused_gators();
-    }
- 
-    bool do_is_equal(const memory_resource& other) const noexcept override {
-        if (this == &other) { return true; }
-        return false;
-    }
-
-	// A suitable pool or upstream resource to allocate and deallocate given bytes
+	// A suitable pool or upstream resource to allocate given bytes
 	memory_resource* resource(std::size_t bytes);
 
-	void cleanup_unused_gators();
-
 private:
 	pool_options options_;
 	std::unique_ptr<memory_resource> owned_upstream_;
@@ -88,6 +77,7 @@ class MemoryPoolResource : public memory_pool_resource {
 	std::vector<std::size_t> pool_block_sizes_;
 	memory_resource* pool_;
 	std::size_t pool_block_size_;
+	mutable std::mutex mtx_;
 };
 
 }
diff --git a/pluto/src/pluto/memory_resource/yakl/YAKL_Gator.h b/pluto/src/pluto/memory_resource/yakl/YAKL_Gator.h
index d0b6a91bd..b3b859a79 100644
--- a/pluto/src/pluto/memory_resource/yakl/YAKL_Gator.h
+++ b/pluto/src/pluto/memory_resource/yakl/YAKL_Gator.h
@@ -237,6 +237,17 @@ namespace yakl {
     };
 
 
+    bool thisIsMyPointer(void *ptr) {
+      std::lock_guard lock(mtx1);
+      // Go through each pool.
+      for (auto it = pools.rbegin() ; it != pools.rend() ; it++) {
+        if (it->thisIsMyPointer(ptr)) {
+          return true;
+        }
+      }
+      return false;
+    }
+
     /** @brief Free the passed pointer, and return the pointer to allocated space.
       * @details Attempting to free a pointer not found in the list of pools will result in a thrown exception */
     void free(void *ptr , char const * label = "" ) {
diff --git a/pluto/tests/CMakeLists.txt b/pluto/tests/CMakeLists.txt
index 0220c2a95..114d4a435 100644
--- a/pluto/tests/CMakeLists.txt
+++ b/pluto/tests/CMakeLists.txt
@@ -12,3 +12,4 @@ add_subdirectory(sandbox)
 
 ecbuild_add_test( TARGET pluto_test_pluto_f SOURCES test_pluto_f.F90 LIBS pluto_f )
 
+ecbuild_add_test( TARGET pluto_test_memory_pool SOURCES pluto_test_memory_pool.cc LIBS pluto )
diff --git a/pluto/tests/pluto_test_memory_pool.cc b/pluto/tests/pluto_test_memory_pool.cc
new file mode 100644
index 000000000..4e6df25e2
--- /dev/null
+++ b/pluto/tests/pluto_test_memory_pool.cc
@@ -0,0 +1,55 @@
+
+/*
+ * (C) Copyright 2024- ECMWF.
+ *
+ * This software is licensed under the terms of the Apache Licence Version 2.0
+ * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
+ * In applying this licence, ECMWF does not waive the privileges and immunities
+ * granted to it by virtue of its status as an intergovernmental organisation
+ * nor does it submit to any jurisdiction.
+ */
+
+#include <iostream>
+#include <cstddef>
+
+#include "pluto/pluto.h"
+
+[[maybe_unused]] constexpr std::size_t kb = 1024;
+[[maybe_unused]] constexpr std::size_t mb = 1024*kb;
+[[maybe_unused]] constexpr std::size_t gb = 1024*mb;
+
+class vector {
+public:
+vector(std::size_t n, const pluto::allocator<std::byte>& alloc) :
+    size_{n},
+    alloc_{alloc} {
+    if (size_) {
+        data_ = alloc_.allocate(size_);
+    }
+}
+~vector() {
+    if(size_) {
+        alloc_.deallocate(data_,size_);
+    }
+}
+std::byte* data_ = nullptr;
+std::size_t size_ = 0;
+pluto::allocator<std::byte> alloc_;
+};
+
+
+int main(int argc, char* argv[]) {
+    std::cout << "BEGIN" << std::endl;
+
+    pluto::TraceOptions::instance().enabled = true;
+
+    pluto::allocator<std::byte> allocator(pluto::pool_resource());
+    // using vector = pluto::host::vector<std::byte>;
+
+    vector array1(200*mb,allocator);
+    vector array2(200*mb,allocator);
+    vector array3(1.2*gb,allocator);
+
+
+    std::cout << "END" << std::endl;
+}