diff --git a/mercurial/httprepo.py b/mercurial/httprepo.py
index 74684e6f49..8c1256f4a1 100644
--- a/mercurial/httprepo.py
+++ b/mercurial/httprepo.py
@@ -17,7 +17,9 @@ def zgenerator(f):
     zd = zlib.decompressobj()
     try:
         for chunk in util.filechunkiter(f):
-            yield zd.decompress(chunk)
+            while chunk:
+                yield zd.decompress(chunk, 2**18)
+                chunk = zd.unconsumed_tail
     except httplib.HTTPException:
         raise IOError(None, _('connection ended unexpectedly'))
     yield zd.flush()
diff --git a/mercurial/merge.py b/mercurial/merge.py
index 8ab9a32e51..a8c769d51d 100644
--- a/mercurial/merge.py
+++ b/mercurial/merge.py
@@ -323,6 +323,7 @@ def applyupdates(repo, action, wctx, mctx, actx):
             repo.ui.note(_("getting %s\n") % f)
             t = mctx.filectx(f).data()
             repo.wwrite(f, t, flags)
+            t = None
             updated += 1
             if f == '.hgsubstate': # subrepo states need updating
                 subrepo.submerge(repo, wctx, mctx, wctx)
diff --git a/mercurial/revlog.py b/mercurial/revlog.py
index ff4912e890..3b4fb415ae 100644
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -1041,6 +1041,9 @@ class revlog(object):
             base = self._cache[1]
             text = self._cache[2]
 
+        # drop cache to save memory
+        self._cache = None
+
         self._loadindex(base, rev + 1)
         self._chunkraw(base, rev)
         if text is None:
diff --git a/mercurial/util.py b/mercurial/util.py
index e1ec36e29b..bd80d0e15a 100644
--- a/mercurial/util.py
+++ b/mercurial/util.py
@@ -925,30 +925,36 @@ class chunkbuffer(object):
                 else:
                     yield chunk
         self.iter = splitbig(in_iter)
-        self.buf = ''
+        self._queue = []
 
     def read(self, l):
         """Read L bytes of data from the iterator of chunks of data.
         Returns less than L bytes if the iterator runs dry."""
-        if l > len(self.buf) and self.iter:
-            # Clamp to a multiple of 2**16
-            targetsize = max(l, 2**16)
-            collector = [str(self.buf)]
-            collected = len(self.buf)
-            for chunk in self.iter:
-                collector.append(chunk)
-                collected += len(chunk)
-                if collected >= targetsize:
+        left = l
+        buf = ''
+        queue = self._queue
+        while left > 0:
+            # refill the queue
+            if not queue:
+                target = 2**18
+                for chunk in self.iter:
+                    queue.append(chunk)
+                    target -= len(chunk)
+                    if target <= 0:
+                        break
+                if not queue:
                     break
-            else:
-                self.iter = False
-            self.buf = ''.join(collector)
-        if len(self.buf) == l:
-            s, self.buf = str(self.buf), ''
-        else:
-            s, self.buf = self.buf[:l], buffer(self.buf, l)
-        return s
 
+            chunk = queue.pop(0)
+            left -= len(chunk)
+            if left < 0:
+                queue.insert(0, chunk[left:])
+                buf += chunk[:left]
+            else:
+                buf += chunk
+
+        return buf
+        
 def filechunkiter(f, size=65536, limit=None):
     """Create a generator that produces the data in the file size
     (default 65536) bytes at a time, up to optional limit (default is
diff --git a/mercurial/verify.py b/mercurial/verify.py
index 9b1556bc0a..8154d3afc6 100644
--- a/mercurial/verify.py
+++ b/mercurial/verify.py
@@ -48,6 +48,8 @@ def _verify(repo):
         if isinstance(inst, KeyboardInterrupt):
             ui.warn(_("interrupted"))
             raise
+        if not str(inst):
+            inst = repr(inst)
         err(linkrev, "%s: %s" % (msg, inst), filename)
 
     def warn(msg):
@@ -229,6 +231,7 @@ def _verify(repo):
 
         checklog(fl, f, lr)
         seen = {}
+        rp = None
         for i in fl:
             revisions += 1
             n = fl.node(i)
@@ -241,12 +244,12 @@ def _verify(repo):
 
             # verify contents
             try:
-                t = fl.read(n)
+                l = len(fl.read(n))
                 rp = fl.renamed(n)
-                if len(t) != fl.size(i):
+                if l != fl.size(i):
                     if len(fl.revision(n)) != fl.size(i):
                         err(lr, _("unpacked size is %s, %s expected") %
-                            (len(t), fl.size(i)), f)
+                            (l, fl.size(i)), f)
             except Exception, inst:
                 exc(lr, _("unpacking %s") % short(n), inst, f)