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Firebird hangs in embed mode [CORE4753] #5057

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firebird-automations opened this issue Apr 16, 2015 · 7 comments
Closed

Firebird hangs in embed mode [CORE4753] #5057

firebird-automations opened this issue Apr 16, 2015 · 7 comments
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@hvlad
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affect-version: 2.5.4 component: engine fix-version: 2.5.5 fix-version: 3.0 Beta 2 priority: major type: bug

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Submitted by: Denis (artden)

Attachments:
FTBugTest.cpp

Firebird embed hangs in isc_attach_database if to execute new application during previous connection exists. Here is my example how to reproduce it (look at HANGS HERE comment):

#⁠include <Windows.h>
#⁠include <string>

#⁠include "ibase.h"

#⁠pragma comment(lib, "fbclient_ms.lib")

const std::string server_and_path = "d:\\DATABASE.FDB";
const std::string process = "C:\\Windows\\System32\\calc.exe";
const unsigned StatusLen = 20;

void connect1()
{
isc_db_handle db_handle = nullptr;
ISC_STATUS status_vect[StatusLen] = {};
char pdb[1] = { isc_dpb_version1 };

// connect 
isc\_attach\_database\(
	status\_vect,
	server\_and\_path\.size\(\),
	server\_and\_path\.c\_str\(\),
	&db\_handle,
	sizeof\(pdb\),
	pdb
\);

// start process

STARTUPINFOA si = \{\};
si\.cb = sizeof\(si\);
PROCESS\_INFORMATION pi = \{\};
int res = CreateProcessA\(
	process\.c\_str\(\),  // lpApplicationName
	NULL,             // lpCommandLine
	NULL,             // lpProcessAttributes
	NULL,             // lpThreadAttributes
	TRUE,             // bInheritHandles
	DETACHED\_PROCESS, // dwCreationFlags
	NULL,             // lpEnvironment
	NULL,             // lpCurrentDirectory
	&si,              // lpStartupInfo
	&pi               // lpProcessInformation
\);

// disconnect
isc\_detach\_database\(status\_vect, &db\_handle\);

}

void connect2()
{
isc_db_handle db_handle = nullptr;
char pdb[1] = { isc_dpb_version1 };

ISC\_STATUS status\_vect\[StatusLen\] = \{\};

// connect
isc\_attach\_database\( // <\- HANGS HERE
	status\_vect,
	server\_and\_path\.size\(\),
	server\_and\_path\.c\_str\(\),
	&db\_handle,
	sizeof\(pdb\),
	pdb
\);

isc\_detach\_database\(status\_vect, &db\_handle\);

}

int main(int argc, char* argv[])
{
connect1();
connect2();
return 0;
}

Commits: 67383e1 840ac35 FirebirdSQL/fbt-repository@b8313be FirebirdSQL/fbt-repository@798bba3
@firebird-automations
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Commented by: Denis (artden)

Example to reproduce

@firebird-automations
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Modified by: Denis (artden)

Attachment: FTBugTest.cpp [ 12705 ]

@firebird-automations
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Modified by: @hvlad

assignee: Vlad Khorsun [ hvlad ]

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Commented by: @hvlad

The reason is that child process by default inherits all handles of parent process.
In our case child process keeps syncronization objects used by Firebird open after parent process detaches database.
At next attempt to attach database engine tries to initialize lock table and failed to "syncronize"
with child process (which have no idea about Firebird).

Obvious workaround is to run child process with bInheritHandles == FALSE, but this is not always possible and
could limit developers of embedded applications.

The proposed fix is to explicitly disable handle inheritance for named syncronization objects used by the engine.

Fix is committed into v2.5 tree, please verify it with next snapshot build.

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Commented by: @hvlad

Simplified test case, using FB3 embedded connection:

firebird>isql c:\temp\A.FDB
Database: c:\temp\A.FDB
SQL> shell start calc;
SQL> connect c:\temp\a.fdb;
Commit current transaction (y/n)?y
Committing.

Hung with high CPU load at this point until calc.exe is terminated.

Database: c:\temp\a.fdb
SQL> exit;

@firebird-automations
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Modified by: @hvlad

status: Open [ 1 ] => Resolved [ 5 ]

resolution: Fixed [ 1 ]

Fix Version: 3.0 Beta 2 [ 10586 ]

Fix Version: 2.5.5 [ 10670 ]

@firebird-automations
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Modified by: @pcisar

status: Resolved [ 5 ] => Closed [ 6 ]

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affect-version: 2.5.4 component: engine fix-version: 2.5.5 fix-version: 3.0 Beta 2 priority: major type: bug
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