Sqlite多线程并发时报空异常

[pardont]

在android上多线程同时读写sqlite数据库时报错，极小概率。在android上运行10几个小时可能会出现下面的错误，在linux和windows上没有这个问题。

在efcore项目中有人遇到类似的问题：
dotnet/efcore#20651

会不会是连接池中的连接池不够用，导致多个线程使用了同一个连接导致的？

构造freesql单实例的代码如下：

_freesql = new FreeSql.FreeSqlBuilder()
                 .UseConnectionString(FreeSql.DataType.Sqlite", Data Source=data.db;")
                 .Build();

在android上运行10几个小时可能会出现下面的错误，在linux和windows上没有这个问题。

12-03 15:40:33.351  1507  2785 V mono-stdout: [Error]: Object reference not set to an instance of an object
12-03 15:40:33.351  1507  2785 V mono-stdout:   at Microsoft.Data.Sqlite.SqliteConnection.RemoveCommand (Microsoft.Data.Sqlite.SqliteCommand command) [0x0001c] in <84cd3138e0a74f0a9108b847408e6ac1>:0 
12-03 15:40:33.351  1507  2785 V mono-stdout:   at Microsoft.Data.Sqlite.SqliteCommand.Dispose (System.Boolean disposing) [0x00014] in <84cd3138e0a74f0a9108b847408e6ac1>:0 
12-03 15:40:33.351  1507  2785 V mono-stdout:   at System.ComponentModel.Component.Dispose () [0x00000] in <71e78ea04782456a9a4e3e211cdabfc0>:0 
12-03 15:40:33.351  1507  2785 V mono-stdout:   at (wrapper remoting-invoke-with-check) System.ComponentModel.Component.Dispose()
12-03 15:40:33.351  1507  2785 V mono-stdout:   at FreeSql.Internal.CommonProvider.AdoProvider.ExecuteReaderMultiple (System.Int32 multipleResult, System.Data.Common.DbConnection connection, System.Data.Common.DbTransaction transaction, System.Action`2[T1,T2] fetchHandler, System.Action`2[T1,T2] schemaHandler, System.Data.CommandType cmdType, System.String cmdText, System.Int32 cmdTimeout, System.Data.Common.DbParameter[] cmdParms) [0x0060f] in <9fbe70c7241946a0b65260e7c7fba30d>:0 
12-03 15:40:33.351  1507  2785 V mono-stdout:   at FreeSql.Internal.CommonProvider.AdoProvider.ExecuteReader (System.Data.Common.DbConnection connection, System.Data.Common.DbTransaction transaction, System.Action`1[T] fetchHandler, System.Data.CommandType cmdType, System.String cmdText, System.Int32 cmdTimeout, System.Data.Common.DbParameter[] cmdParms) [0x0000d] in <9fbe70c7241946a0b65260e7c7fba30d>:0 
12-03 15:40:33.351  1507  2785 V mono-stdout:   at FreeSql.Internal.CommonProvider.Select0Provider`2[TSelect,T1].ToListAfPrivate (System.String sql, FreeSql.Internal.CommonProvider.Select0Provider`2+GetAllFieldExpressionTreeInfo[TSelect,T1] af, FreeSql.Internal.Model.ReadAnonymousTypeOtherInfo[] otherData) [0x000eb] in <9fbe70c7241946a0b65260e7c7fba30d>:0 
12-03 15:40:33.351  1507  2785 V mono-stdout:   at FreeSql.Internal.CommonProvider.Select0Provider`2[TSelect,T1].ToListPrivate (FreeSql.Internal.CommonProvider.Select0Provider`2+GetAllFieldExpressionTreeInfo[TSelect,T1] af, FreeSql.Internal.Model.ReadAnonymousTypeOtherInfo[] otherData) [0x0014e] in <9fbe70c7241946a0b65260e7c7fba30d>:0 
12-03 15:40:33.351  1507  2785 V mono-stdout:   at FreeSql.Internal.CommonProvider.Select0Provider`2[TSelect,T1].ToList (System.Boolean includeNestedMembers) [0x000ce] in <9fbe70c7241946a0b65260e7c7fba30d>:0 
12-03 15:40:33.351  1507  2785 V mono-stdout:   at FreeSql.Internal.CommonProvider.Select1Provider`1[T1].ToList (System.Boolean includeNestedMembers) [0x00000] in <9fbe70c7241946a0b65260e7c7fba30d>:0 
12-03 15:40:33.351  1507  2785 V mono-stdout:   at FreeSql.Internal.CommonProvider.Select0Provider`2[TSelect,T1].ToList () [0x00000] in <9fbe70c7241946a0b65260e7c7fba30d>:0 
12-03 15:40:33.351  1507  2785 V mono-stdout:   at Wisdor.POS.Data.Services.Sqlite.SaleSummaryService.GetUnuploadBills (System.Int32 limit) [0x000f2] in <db439cfd6ace4be494971b781933cd50>:0 
12-03 15:40:33.357   292  2788 V [email protected]: @dequeueV4l2FrameLocked(3866) select time begin 
12-03 15:40:33.362  1507  1507 V mono-stdout: [Error]: Object reference not set to an instance of an object
12-03 15:40:33.362  1507  1507 V mono-stdout:   at Microsoft.Data.Sqlite.SqliteConnection.RemoveCommand (Microsoft.Data.Sqlite.SqliteCommand command) [0x0001c] in <84cd3138e0a74f0a9108b847408e6ac1>:0 
12-03 15:40:33.362  1507  1507 V mono-stdout:   at Microsoft.Data.Sqlite.SqliteCommand.Dispose (System.Boolean disposing) [0x00014] in <84cd3138e0a74f0a9108b847408e6ac1>:0 
12-03 15:40:33.363  1507  1507 V mono-stdout:   at System.ComponentModel.Component.Dispose () [0x00000] in <71e78ea04782456a9a4e3e211cdabfc0>:0 
12-03 15:40:33.363  1507  1507 V mono-stdout:   at (wrapper remoting-invoke-with-check) System.ComponentModel.Component.Dispose()
12-03 15:40:33.363  1507  1507 V mono-stdout:   at FreeSql.Internal.CommonProvider.AdoProvider.ExecuteReaderMultiple (System.Int32 multipleResult, System.Data.Common.DbConnection connection, System.Data.Common.DbTransaction transaction, System.Action`2[T1,T2] fetchHandler, System.Action`2[T1,T2] schemaHandler, System.Data.CommandType cmdType, System.String cmdText, System.Int32 cmdTimeout, System.Data.Common.DbParameter[] cmdParms) [0x0060f] in <9fbe70c7241946a0b65260e7c7fba30d>:0 
12-03 15:40:33.363  1507  1507 V mono-stdout:   at FreeSql.Internal.CommonProvider.AdoProvider.ExecuteReader (System.Data.Common.DbConnection connection, System.Data.Common.DbTransaction transaction, System.Action`1[T] fetchHandler, System.Data.CommandType cmdType, System.String cmdText, System.Int32 cmdTimeout, System.Data.Common.DbParameter[] cmdParms) [0x0000d] in <9fbe70c7241946a0b65260e7c7fba30d>:0 
12-03 15:40:33.363  1507  1507 V mono-stdout:   at FreeSql.Internal.CommonProvider.Select0Provider`2[TSelect,T1].ToListAfPrivate (System.String sql, FreeSql.Internal.CommonProvider.Select0Provider`2+GetAllFieldExpressionTreeInfo[TSelect,T1] af, FreeSql.Internal.Model.ReadAnonymousTypeOtherInfo[] otherData) [0x000eb] in <9fbe70c7241946a0b65260e7c7fba30d>:0 
12-03 15:40:33.363  1507  1507 V mono-stdout:   at FreeSql.Internal.CommonProvider.Select0Provider`2[TSelect,T1].ToListPrivate (FreeSql.Internal.CommonProvider.Select0Provider`2+GetAllFieldExpressionTreeInfo[TSelect,T1] af, FreeSql.Internal.Model.ReadAnonymousTypeOtherInfo[] otherData) [0x0014e] in <9fbe70c7241946a0b65260e7c7fba30d>:0 
12-03 15:40:33.363  1507  1507 V mono-stdout:   at FreeSql.Internal.CommonProvider.Select0Provider`2[TSelect,T1].ToList (System.Boolean includeNestedMembers) [0x000ce] in <9fbe70c7241946a0b65260e7c7fba30d>:0 
12-03 15:40:33.363  1507  1507 V mono-stdout:   at FreeSql.Internal.CommonProvider.Select1Provider`1[T1].ToList (System.Boolean includeNestedMembers) [0x00000] in <9fbe70c7241946a0b65260e7c7fba30d>:0 
12-03 15:40:33.363  1507  1507 V mono-stdout:   at FreeSql.Internal.CommonProvider.Select0Provider`2[TSelect,T1].ToList () [0x00000] in <9fbe70c7241946a0b65260e7c7fba30d>:0 
12-03 15:40:33.363  1507  1507 V mono-stdout:   at FreeSql.Internal.CommonProvider.Select0Provider`2[TSelect,T1].ToOne () [0x00009] in <9fbe70c7241946a0b65260e7c7fba30d>:0 
12-03 15:40:33.363  1507  1507 V mono-stdout:   at FreeSql.Internal.CommonProvider.Select0Provider`2[TSelect,T1].First () [0x00000] in <9fbe70c7241946a0b65260e7c7fba30d>:0 
12-03 15:40:33.363  1507  1507 V mono-stdout:   at Wisdor.POS.Data.Services.Sqlite.PluService.QueryRow (System.String barcode) [0x0008f] in <db439cfd6ace4be494971b781933cd50>:0 
12-03 15:40:33.363  1507  1507 V mono-stdout:   at Wisdor.POS.BLL.Default.BarcodeLogic.ProcessBarcode (System.String barcode, System.Object extensionData) [0x001fd] in <db439cfd6ace4be494971b781933cd50>:0 

数据库版本

Sqlite3

安装的Nuget包

FreeSql: 3.2.682
FreeSql.Provider.Sqlite: 3.2.682
Microsoft.Data.Sqlite: 6.0.10

.net framework/. net core？ 及具体版本

Xamarin.Forms: 5.0.0.1874

[2881099]

sqlite不支持多线程写

[pardont]

有什么推荐的做法吗？我在linux和windows上也是相同的程序写法，没有问题呀

[pardont]

sqlite不支持多线程写

有没有什么思路或者建议？从Microsoft.Data.Sqlite库那边的描述是说要避免多线程使用同一个连接，是不是可以从FreeSql的连接池着手？

[2881099]

freesql 层面每次都是独立的 DbConnection

[pardont]

sqlite不支持多线程写

我测试了一下，在数据库中插入了1000多条数据，然后开了10个线程读取数据，不做写操作，就会出现空异常

2-03 15:40:33.351  1507  2785 V mono-stdout: [Error]: Object reference not set to an instance of an object
12-03 15:40:33.351  1507  2785 V mono-stdout:   at Microsoft.Data.Sqlite.SqliteConnection.RemoveCommand (Microsoft.Data.Sqlite.SqliteCommand command) [0x0001c] in <84cd3138e0a74f0a9108b847408e6ac1>:0 
12-03 15:40:33.351  1507  2785 V mono-stdout:   at Microsoft.Data.Sqlite.SqliteCommand.Dispose (System.Boolean disposing) [0x00014] in <84cd3138e0a74f0a9108b847408e6ac1>:0 

如果在多线程操作中再加上写操作，会出现数据库被锁定的异常。

所以多线程只是读取数据，会出现空异常，是不是说明同一个数据库连接在同一个时间点上被多个线程使用了？

[2881099]

用 FreeSql.provider.Sqlite.dll 测试一下

[2881099]

同时用一个 DbConnection 读是不可能的，如果有早就有人反馈了。

[pardont]

FreeSql.provider.Sqlite.dll 没办法在android上跑吧。

我把库都升级到最新，概率大幅下降了，原本10线程在android上大概700-800次就会出现，升级后大概大几千次出现一次。

我暂时的想法是把所有的调用代码都加上try catch处理掉