Sunkwan-Kwon opened a new issue #5626: Memory leak of pulsar-function-go library regarding time.NewTimer() URL: https://github.com/apache/pulsar/issues/5626 **Describe the bug** There is a memory leak in the pulsar-function-go library. I reported an issue regarding the package(#5589), but this report is another one. It is related to KillAfterIdleMs configuration value. If I set the value to 0, time.NewTimer() function has occupied more memory indefinitely. Refer to `pprof ` result of that below. ``` # go tool pprof -top http://localhost:6060/debug/pprof/heap Fetching profile over HTTP from http://localhost:6060/debug/pprof/heap Saved profile in /root/pprof/pprof.simple-worker.alloc_objects.alloc_space.inuse_objects.inuse_space.713.pb.gz File: simple-worker Build ID: 2a730ff40dbea9318c3ce868f33ecc2e69304de8 Type: inuse_space Time: Nov 12, 2019 at 12:27pm (KST) Showing nodes accounting for 31.29MB, 100% of 31.29MB total flat flat% sum% cum cum% 30MB 95.88% 95.88% 31.29MB 100% time.NewTimer 1.29MB 4.12% 100% 1.29MB 4.12% time.startTimer 0 0% 100% 31.29MB 100% github.com/apache/pulsar/pulsar-function-go/pf.(*goInstance).startFunction 0 0% 100% 31.29MB 100% github.com/apache/pulsar/pulsar-function-go/pf.Start 0 0% 100% 31.29MB 100% main.main 0 0% 100% 31.29MB 100% runtime.main 0 0% 100% 31.29MB 100% time.After ``` If I set `KillAfterIdleMs` value higher than 0, the memory leak didn't appear. In order to fix this issue, I investigated the source code and I could find the code that caused the problem. Fortunately, It seems has been fixed now. So I will send a pull request for that. **To Reproduce** Steps to reproduce the behavior: 1. Prepare a pulsar cluster with standalone mode. 2. Prepare a simple pulsar function worker. Refer to the codes below. ``` $ cat simple-worker.go package main import ( "context" "fmt" "net/http" _ "net/http/pprof" "github.com/apache/pulsar/pulsar-function-go/pf" ) func main() { // go routine for pprof go func() { fmt.Println("%+v", http.ListenAndServe("localhost:6060", nil)) }() pf.Start(testFunction) } func testFunction(ctx context.Context) { fmt.Printf("Hello\n") } ``` 3. Prepare a conf.yaml file for the function worker. ``` --- pulsarServiceURL: "pulsar://sunkwan-devpc:6650" instanceID: 0 funcID: "ed5f48f4-8e76-4d30-8b88-6eea1ff3cbf3" funcVersion: "12f361a0-67e5-4404-8177-8c328a33e3db" maxBufTuples: 1024 port: 0 clusterName: "standalone" killAfterIdleMs: 0 tenant: "public" nameSpace: "default" name: "func-concat" className: '' #logTopic: 'persistent://public/default/func-concat-logs' logTopic: '' processingGuarantees: 0 secretsMap: '' runtime: 0 autoAck: true parallelism: 3 subscriptionType: 0 timeoutMs: 0 subscriptionName: '' cleanupSubscription: true sourceSpecsTopic: "persistent://public/default/func-concat" sourceSchemaType: '' receiverQueueSize: 1 #sinkSpecsTopic: "persistent://public/default/func-concat-output" #sinkSpecsTopic: "" #sinkSchemaType: '' #cpu: 1 #ram: 1073741824 #disk: 10737418240 #maxMessageRetries: 0 #deadLetterTopic: '' #regexPatternSubscription: false ``` 4. Execute the simple pulsar function worker by command line below. ``` ./simple-worker --instance-conf-path ./conf.yaml ``` 5. Send messages to the input topic consecutively. 6. Check the memory usage and heap status using pprof. ``` # go tool pprof -top http://localhost:6060/debug/pprof/heap Fetching profile over HTTP from http://localhost:6060/debug/pprof/heap Saved profile in /root/pprof/pprof.simple-worker.alloc_objects.alloc_space.inuse_objects.inuse_space.713.pb.gz File: simple-worker Build ID: 2a730ff40dbea9318c3ce868f33ecc2e69304de8 Type: inuse_space Time: Nov 12, 2019 at 12:27pm (KST) Showing nodes accounting for 31.29MB, 100% of 31.29MB total flat flat% sum% cum cum% 30MB 95.88% 95.88% 31.29MB 100% time.NewTimer 1.29MB 4.12% 100% 1.29MB 4.12% time.startTimer 0 0% 100% 31.29MB 100% github.com/apache/pulsar/pulsar-function-go/pf.(*goInstance).startFunction 0 0% 100% 31.29MB 100% github.com/apache/pulsar/pulsar-function-go/pf.Start 0 0% 100% 31.29MB 100% main.main 0 0% 100% 31.29MB 100% runtime.main 0 0% 100% 31.29MB 100% time.After ``` **Expected behavior** - Memory usage of pulsar worker process shouldn't be grown indefinitely. **Screenshots** N/A **Desktop (please complete the following information):** - OS: Ubuntu 18.04 **Additional context** N/A
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