Print the end of the log

swh/graph/cli.py

@@ -6,6 +6,7 @@
 import logging
 from pathlib import Path
 import shlex
+import sys
 from typing import TYPE_CHECKING, Any, Dict, List, Optional, Set, Tuple
 
 # WARNING: do not import unnecessary things here to keep cli startup time under
@@ -257,7 +258,21 @@ def compress(ctx, input_dataset, output_directory, graph_name, steps):
     try:
         webgraph.compress(graph_name, input_dataset, output_directory, steps, conf)
     except webgraph.CompressionSubprocessError as e:
-        raise click.ClickException(e.args[0])
+        try:
+            if e.log_path.is_file():
+                with e.log_path.open("rb") as f:
+                    if e.log_path.stat().st_size > 1000:
+                        f.seek(-1000, 2)  # read only the last 1kB
+                        f.readline()  # skip first line, might be partial
+                        sys.stderr.write("[...]\n")
+                    sys.stderr.write("\n")
+                    sys.stderr.flush()
+                    sys.stderr.buffer.write(f.read())
+                    sys.stderr.flush()
+        except Exception:
+            raise
+            pass
+        raise click.ClickException(e.message)
 
 
 def get_all_subclasses(cls):

swh/graph/webgraph.py

@@ -24,7 +24,10 @@ logger = logging.getLogger(__name__)
 
 
 class CompressionSubprocessError(Exception):
-    pass
+    def __init__(self, message: str, log_path: Path):
+        super().__init__(f"{message}; full logs at {log_path}")
+        self.message = message
+        self.log_path = log_path
 
 
 class CompressionStep(Enum):
@@ -328,7 +331,7 @@ def do_step(step, conf):
     rc = process.wait()
     if rc != 0:
         raise CompressionSubprocessError(
-            f"Compression step {step} returned non-zero exit code {rc}, see {log_path}"
+            f"Compression step {step} returned non-zero exit code {rc}", log_path
         )
     step_end_time = datetime.now()
     step_duration = step_end_time - step_start_time