Merge pull request #6137 from Komnomnomnom/json-0.13-slowdown

PERF: fix JSON performance regression from 0.12 (GH5765)

Author: jreback

doc/source/release.rst

@@ -119,6 +119,7 @@ Bug Fixes
   - Regresssion in handling of empty Series as indexers to Series  (:issue:`5877`)
   - Bug in internal caching, related to (:issue:`5727`)
   - Testing bug in reading json/msgpack from a non-filepath on windows under py3 (:issue:`5874`)
+  - Fix performance regression in JSON IO (:issue:`5765`)
   - Bug when assigning to .ix[tuple(...)] (:issue:`5896`)
   - Bug in fully reindexing a Panel (:issue:`5905`)
   - Bug in idxmin/max with object dtypes (:issue:`5914`)

pandas/src/ujson/lib/ultrajsondec.c

@@ -894,15 +894,23 @@ JSOBJ JSON_DecodeObject(JSONObjectDecoder *dec, const char *buffer, size_t cbBuf
 
   ds.dec = dec;
 
-  locale = strdup(setlocale(LC_NUMERIC, NULL));
-  if (!locale)
+  locale = setlocale(LC_NUMERIC, NULL);
+  if (strcmp(locale, "C"))
   {
-    return SetError(&ds, -1, "Could not reserve memory block");
+    locale = strdup(locale);
+    if (!locale)
+    {
+      return SetError(&ds, -1, "Could not reserve memory block");
+    }
+    setlocale(LC_NUMERIC, "C");
+    ret = decode_any (&ds);
+    setlocale(LC_NUMERIC, locale);
+    free(locale);
+  }
+  else 
+  {
+    ret = decode_any (&ds);
   }
-  setlocale(LC_NUMERIC, "C");
-  ret = decode_any (&ds);
-  setlocale(LC_NUMERIC, locale);
-  free(locale);
 
   if (ds.escHeap)
   {

pandas/src/ujson/lib/ultrajsonenc.c

@@ -917,16 +917,24 @@ char *JSON_EncodeObject(JSOBJ obj, JSONObjectEncoder *enc, char *_buffer, size_t
   enc->end = enc->start + _cbBuffer;
   enc->offset = enc->start;
 
-  locale = strdup(setlocale(LC_NUMERIC, NULL));
-  if (!locale)
+  locale = setlocale(LC_NUMERIC, NULL);
+  if (strcmp(locale, "C"))
   {
-    SetError(NULL, enc, "Could not reserve memory block");
-    return NULL;
+    locale = strdup(locale);
+    if (!locale)
+    {
+      SetError(NULL, enc, "Could not reserve memory block");
+      return NULL;
+    }
+    setlocale(LC_NUMERIC, "C");
+    encode (obj, enc, NULL, 0);
+    setlocale(LC_NUMERIC, locale);
+    free(locale);
+  }
+  else 
+  {
+    encode (obj, enc, NULL, 0);
   }
-  setlocale(LC_NUMERIC, "C");
-  encode (obj, enc, NULL, 0);
-  setlocale(LC_NUMERIC, locale);
-  free(locale);
 
   Buffer_Reserve(enc, 1);
   if (enc->errorMsg)