fix: suppress stdout and stderr in Jupyter notebooks (abetlen#2181)

Co-authored-by: Anai-Guo <275560793+Anai-Guo@users.noreply.github.com>

Author: Anai-Guo

CHANGELOG.md

@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+- fix: suppress stdout and stderr in Jupyter notebooks by @Anai-Guo in #2181
 - feat: enable arm64 musl builds by @acon96 in #2221
 - feat: Update llama.cpp to ggml-org/llama.cpp@d749821db
 - fix: model fails to load when chat template uses HuggingFace generation tags by @tobocop2 in #2226

llama_cpp/_utils.py

@@ -34,6 +34,22 @@ def __enter__(self):
         self.old_stdout = self.sys.stdout
         self.old_stderr = self.sys.stderr
 
+        # In Jupyter notebooks, ipykernel replaces sys.stdout/stderr with
+        # OutStream objects that hold their own copy of the original fd in
+        # _original_stdstream_copy. This bypasses our dup2 redirect, so we
+        # need to point that copy at the real fd temporarily.
+        # https://github.com/ipython/ipykernel/blob/912923542d55e6c80c0e7c1f94c648b52a225011/ipykernel/iostream.py#L618-L622
+        self._saved_stdout_copy = getattr(
+            self.sys.stdout, "_original_stdstream_copy", None
+        )
+        self._saved_stderr_copy = getattr(
+            self.sys.stderr, "_original_stdstream_copy", None
+        )
+        if self._saved_stdout_copy is not None:
+            self.sys.stdout._original_stdstream_copy = self.old_stdout_fileno_undup
+        if self._saved_stderr_copy is not None:
+            self.sys.stderr._original_stdstream_copy = self.old_stderr_fileno_undup
+
         self.os.dup2(outnull_file.fileno(), self.old_stdout_fileno_undup)
         self.os.dup2(errnull_file.fileno(), self.old_stderr_fileno_undup)
 
@@ -45,7 +61,6 @@ def __exit__(self, *_):
         if self.disable:
             return
 
-        # Check if sys.stdout and sys.stderr have fileno method
         self.sys.stdout = self.old_stdout
         self.sys.stderr = self.old_stderr
 
@@ -55,6 +70,12 @@ def __exit__(self, *_):
         self.os.close(self.old_stdout_fileno)
         self.os.close(self.old_stderr_fileno)
 
+        # Restore ipykernel's OutStream fd copies
+        if self._saved_stdout_copy is not None:
+            self.sys.stdout._original_stdstream_copy = self._saved_stdout_copy
+        if self._saved_stderr_copy is not None:
+            self.sys.stderr._original_stdstream_copy = self._saved_stderr_copy
+
 
 class MetaSingleton(type):
     """