[jira] Created: (COUCHDB-982) [PATCH] couchdb won't work with debug version of spidermonkey

["Petr Běhan (JIRA)" <ji...@apache.org>]

[PATCH] couchdb won't work with debug version of spidermonkey
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                 Key: COUCHDB-982
                 URL: https://issues.apache.org/jira/browse/COUCHDB-982
             Project: CouchDB
          Issue Type: Bug
          Components: Database Core
    Affects Versions: 1.0.1
            Reporter: Petr Běhan
            Priority: Minor


Steps to reproduce:
1) configure spidermonkey with --enable-debug --enable-threadsafe and compile it
2) make couchdb use it (in my case install it as system-wide library, or through LD_LIBRARY_PATH)
3) restart couchdb server
4) attempt to query any view via http

Observed behaviour:
View query returns nothing, server pegs all CPUs, top shows nothing (spawned children die too fast to register on top) and /var/log/couchdb/couch.log starts filling with lines similar to "[Wed, 08 Dec 2010 21:59:37 GMT] [error] [<0.205.0>] OS Process Error <0.1056.0> :: {os_process_error,{exit_status,134}}" at rate of about 70 errors per second (which itself is a separate bug in my opinion, it should attempt to call the child once, and if it fails, stop further attempts and notify client of http/500 error)

Problem is in incorrect use of JS_DestroyContext call. JSAPI documentation says that the context being destroyed may or may not be inside active request. But it doesn't explicitly mention that the calling thread MUST be set as current for the context. In src/couchdb/priv/couch_js/main.c, the macro FINISH_REQUEST incorrectly calls JS_ClearContextThread, which is intended to TRANSFER the context to another thread instead. The JS_DestroyContext call then triggers spidermonkey assert.

Since "JS_NewContext automatically associates the new context with the calling thread.", I think the thread stuff should be completely dropped from both SETUP_REQUEST and FINISH_REQUEST macros and let spidermonkey take care of itself (unless there are plans to add threads to couch_js in future). Following simple patch fixes couchdb on my system:

--- src/couchdb/priv/couch_js/main.c.orig       2010-12-09 00:40:40.000000000 +0100
+++ src/couchdb/priv/couch_js/main.c    2010-12-09 01:03:34.000000000 +0100
@@ -23,11 +23,9 @@

 #ifdef JS_THREADSAFE
 #define SETUP_REQUEST(cx) \
-    JS_SetContextThread(cx); \
     JS_BeginRequest(cx);
 #define FINISH_REQUEST(cx) \
-    JS_EndRequest(cx); \
-    JS_ClearContextThread(cx);
+    JS_EndRequest(cx);
 #else
 #define SETUP_REQUEST(cx)
 #define FINISH_REQUEST(cx)

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