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I use the event to execute a query in mysql database with nodejs, the first 5 times execute normally, but after 5 times return an error "Lock wait timeout exceeded; try restarting transaction". What happened and how can i solve this?
I use Mysql database.

 emitter.on('mysql.transact', function(data, callback) 

 inTransaction(pool, 
 function(db, next) 
 //console.log('======');
 //console.log(data.q);
 //console.log(data.v);
 db.query(data.q, data.v, function(err) 
 if (err) return next(err);
 return callback(null,data);
 ), 
 function(err) 
 console.log("All done, transaction ended and connection released");
 console.log(err);
 
 );
); 

function inTransaction(pool, body, callback) 
 withConnection(pool, function(db, done) 
 //console.log('123');
 //console.log(db);
 db.beginTransaction(function(err) 
 if (err) return done(err);

 body(db,finished)
 )

 // Commit or rollback transaction, then proxy callback
 function finished(err) 
 var context = this;
 var args = arguments;

 if (err) 
 if (err == 'rollback') 
 args[0] = err = null;
 
 db.rollback(function() done.apply(context, args) );
 else 
 db.commit(function(err) 
 args[0] = err;
 done.apply(context, args)
 )
 
 
 , callback)


function withConnection(pool, body, callback) 

 pool.getConnection(function(err, db) 
 if (err) return callback(err);

 body(db, finished); 
 function finished() 
 db.release();
 callback.apply(this, arguments);
 
 )

=========

Here is a query that i tried to execute with nodejs

 var q = ' UPDATE data_alarm set HideAlarmFrom = NULL, '+
 ' HideAlarmText = NULL ' +
 ' Where VariableID in (select VariableID from dbo_v_reportvariables' +
 ' where ClientID = ? ' +
 ' and SiteID in (select SiteID from dbo_v_accesslist where UserID = ? ) ) ';

var v = [req.user.ClientID,req.user.UserID];

exp.emitter.emit('mysql.transact', q: q, v : v , function(err, data) 
 if (err) 
 res.status(500).json( error : err ); 
 else 
 res.status(200).json(data); 
 
 );