Call malloc_trim(0) on Linux

src/command_line.cc

@@ -2623,6 +2623,10 @@ void QueryDbMain(const std::string& bin_name, Config* config, MultiQueueWaiter*
       config, &db, waiter, &queue,
       &project, &file_consumer_shared, &import_manager, &timestamp_manager, &working_files,
       &clang_complete, &include_complete, global_code_complete_cache.get(), non_global_code_complete_cache.get(), signature_cache.get());
+
+    // Cleanup and free any unused memory.
+    FreeUnusedMemory();
+
     if (!did_work) {
       waiter->Wait({
         IpcManager::instance()->threaded_queue_for_server_.get(),

src/platform.h

@@ -50,4 +50,7 @@ void CopyFileTo(const std::string& destination, const std::string& source);
 bool IsSymLink(const std::string& path);
 
 // Returns any clang arguments that are specific to the current platform.
-std::vector<std::string> GetPlatformClangArguments();
+std::vector<std::string> GetPlatformClangArguments();
+
+// Free any unused memory and return it to the system.
+void FreeUnusedMemory();

src/platform_linux.cc

@@ -5,6 +5,7 @@
 
 #include <loguru.hpp>
 
+#include <malloc.h>
 #include <cassert>
 #include <string>
 #include <pthread.h>
@@ -247,4 +248,8 @@ std::vector<std::string> GetPlatformClangArguments() {
 }
 #undef CHECKED
 
+void FreeUnusedMemory() {
+  malloc_trim(0);
+}
+
 #endif

src/platform_win.cc

@@ -226,4 +226,7 @@ std::vector<std::string> GetPlatformClangArguments() {
     "-fdelayed-template-parsing"
   };
 }
+
+void FreeUnusedMemory() {}
+
 #endif