Bugs item #2860037, was opened at 2009-09-16 16:33
Message generated for change (Settings changed) made by tsheyar
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Category: PF general
Group: Pathfinder "stable"
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Axel Belinfante (axelbel)
>Assigned to: Sjoerd Mullender (sjoerd)
Summary: fatal error: aborted too deep recursion on linux
Initial Comment:
attempting to run the attached xquery results in fatal error: aborted too deep
recursion.
replacing the call to processISBN(...) by () is sufficient to 'make it
work'.
to reproduce this, it is sufficient to add a document named eprints-export.xml
with contents
<repository/>
mclient -lx -p 51012 ./convexport-dummy.xq
MAPI = mone...@localhost:51012
QUERY = declare function processISBN($fields as element()*) as element()*
ERROR = !fatal error: aborted too deep recursion
!# halted in mil_dce.c (mil_dce_worker), line 146
this is with the aug-2009 monetdb (same with the may-2009) release,
on linux:
Linux ewi865 2.6.16.21-0.8-smp #1 SMP Mon Jul 3 18:25:39 UTC 2006 x86_64 x86_64
x86_64 GNU/Linux
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>Comment By: Jan Rittinger (tsheyar)
Date: 2009-09-28 14:55
Message:
A MIL program is internally represented as a tree. Assignments are
separated by a seq operator (that builds a sequence). As the code
generation builds programs in a left-deep manner the nesting depth in
mil_dce.c depends on the number of seq operators (and thus also indirectly
on the number of MIL code lines). The conclusion is: the bigger the
program, the deeper the nesting becomes.
In the attached example the DCE sees a nesting depth of ~12.400.
It seems awkward to me to produce 'bushy' MIL plans to stay alive longer.
A better solution would be to adjust the tree walker to handle operator seq
separately and avoid the recursion fence alltogether.
Sjoerd, do you have any favourite solution in mind?
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Comment By: Stefan Manegold (stmane)
Date: 2009-09-24 15:58
Message:
This looks like when embedded in Mserver, the pf compiler (or its
optimizer) requires more stack space (due to deep recursion) than available
to compile/optimize your query:
$ diff -du /tmp/convexport.xq /tmp/convexport-dummy.xq
--- /tmp/convexport.xq 2009-09-24 15:40:01.000000000 +0200
+++ /tmp/convexport-dummy.xq 2009-09-24 15:41:47.000000000 +0200
@@ -54,7 +54,7 @@
let $ed := processNames("editor",$fl...@name eq "editors"])
let $sup := processNames("supervisor",$fl...@name eq "supervisors"])
let $asup := processNames("assistant_supervisor",$fl...@name eq
"assistant_supervisors"])
- let $isbn := processISBN($fl...@name eq "isbn" or @name eq
"isbn_13"])
+ let $isbn := ($fl...@name eq "isbn" or @name eq
"isbn_13"])
let $ep :=
<eprint>{
$cr,$ed,$sup,$asup,$isbn,
$ pf /tmp/convexport.xq > /tmp/convexport.mil
$ wc /tmp/convexport.mil
15179 60656 537972 /tmp/convexport.mil
$ pf /tmp/convexport-dummy.xq > /tmp/convexport-dummy.mil
$ wc /tmp/convexport-dummy.mil
13515 53969 478507 /tmp/convexport-dummy.mil
$ cat /tmp/eprints-export.xml
<repository/>
$ mclient -lx
-s'pf:add-doc("/tmp/eprints-export.xml","eprints-export.xml")'
$ mclient -lx -s'doc("eprints-export.xml")'
<?xml version="1.0" encoding="utf-8"?>
<repository/>
$ pf /tmp/convexport-dummy.xq | mclient -lmil
<?xml version="1.0" encoding="utf-8"?>
<XQueryResult><repository/></XQueryResult>
$ pf /tmp/convexport.xq | mclient -lmil
<?xml version="1.0" encoding="utf-8"?>
<XQueryResult><repository/></XQueryResult>
$ mclient -lx /tmp/convexport-dummy.xq
MAPI = mone...@localhost:50000
QUERY = declare function processISBN($fields as element()*) as element()*
ERROR = !fatal error: aborted too deep recursion
!# halted in
/ufs/manegold/_/scratch0/Monet/Testing/Stable/source/pathfinder/compiler/mil/mil_dce.c
(mil_dce_worker), line 146
$ mclient -lx /tmp/convexport.xq
MAPI = mone...@localhost:50000
QUERY = declare function processISBN($fields as element()*) as element()*
ERROR = !fatal error: aborted too deep recursion
!# halted in
/ufs/manegold/_/scratch0/Monet/Testing/Stable/source/pathfinder/compiler/mil/mil_dce.c
(mil_dce_worker), line 146
Maybe Jan has some idea or comment?
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