• The previous unbounded queue constantly reallocated memory, risking system memory exhaustion, especially when handling intensive logging from multiple threads. Starting from v3.0.0, the default behavior has been improved to limit the queue capacity to 2 GB. When this limit is reached, the queue blocks the hot thread instead of further reallocation. To modify the default behavior, there is no need to recompile the quill library. Recompile your application with one of the following header-only flags.

# Previous behavior in v2.*.*: Reallocates new queues indefinitely when max capacity is reached
-DCMAKE_CXX_FLAGS:STRING="-DQUILL_USE_UNBOUNDED_NO_MAX_LIMIT_QUEUE"

# Default behavior in v3.*.*: Starts small, reallocates up to 2GB, then hot thread blocks
-DCMAKE_CXX_FLAGS:STRING="-DQUILL_USE_UNBOUNDED_BLOCKING_QUEUE"

# Starts small, reallocates up to 2GB, then hot thread drops log messages
-DCMAKE_CXX_FLAGS:STRING="-DQUILL_USE_UNBOUNDED_DROPPING_QUEUE"

# Fixed queue size, no reallocations, hot thread drops log messages
-DCMAKE_CXX_FLAGS:STRING="-DQUILL_USE_BOUNDED_QUEUE"         

# Fixed queue size, no reallocations, hot thread blocks
-DCMAKE_CXX_FLAGS:STRING="-DQUILL_USE_BOUNDED_BLOCKING_QUEUE"

• Added support for huge pages on Linux. Enabling this feature allows bounded or unbounded queues to utilize huge pages, resulting in optimized memory allocation.

  quill::Config cfg;
  cfg.enable_huge_pages_hot_path = true;
  
  quill::configure(cfg);
  quill::start();

• Added support for logging std::optional, which is also now supported in libfmt v10.0.0.

  LOG_INFO(default_logger, "some optionals [{}, {}]", std::optional<std::string>{},
           std::optional<std::string>{"hello"});

• Introduced a new function run_loop in the Handler base class, which allows users to override and execute periodic tasks. This enhancement provides users with the flexibility to perform various actions at regular intervals, such as batch committing data to a database.
• In scenarios where a hot thread is blocked and unable to push messages to the queue in blocking mode, this situation will now be reported through the backend_thread_notifications_handler to the standard error stream cerr.